Scielo RSS <![CDATA[Salud mental]]> http://www.scielo.org.mx/rss.php?pid=0185-332520100005&lang=pt vol. 33 num. 5 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.org.mx/img/en/fbpelogp.gif http://www.scielo.org.mx <![CDATA[<b>Cost-effectiveness study of interventions to prevent alcohol abuse in Mexico</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500001&lng=pt&nrm=iso&tlng=pt Introduction In Mexico, alcohol abuse involves overhead costs in terms of premature mortality caused by their related health problems. It is estimated that by itself it implies 9% of the total burden of disease in the country. Although effective interventions exist to treat this problem, national public policies are not integrated and in many occasions its real application is questioned. Cost-effectiveness studies are tools that permit to develop and to implement health public policies because they imply a rigorous economic evaluation and comparison of those in order to determine which obtains better balance between effectiveness and financial viability. Thus, the aim of the present study was to determine the cost-effectiveness of interventions to prevent and to control alcohol abuse in Mexico, based on the proposed methodology by the World Health Organization. It will permit to generate national public policies with local evidence and to carry out evaluations of their impact, as well as international comparisons. Method The World Health Organization methodology named WHO-CHOICE (CHOosing the Interventions that are Cost-Effective) was developed to evaluate and to select the most cost-effective interventions for the prevention or treatment of health problems. It is considered a generalized cost-effective analysis; therefore direct or tangible costs are particularly analyzed (vs. indirect or intangible costs). Procedure First, WHO-CHOICE analysis requires information from different sources about both the illness or problem and the preventive or therapeutic interventions to evaluate. Then, information is processed by special software. As annual standard discount of 3% is done to obtain and to compare the present supplies values; and age of individuals is praised, giving more weight to the young phases. Finally, the results are presented in terms of intervention cost-effectiveness to reduce the burden of disease, defined in terms of disability adjusted life years or DALYs. Interventions The following interventions were evaluated: 1. Current Setting: Taxes and random tests for the detection of alcoholic breath (breathalyzer); 2. Increment of 25% to taxes of products with harmful degree of alcohol; 3. Increment of 50% to taxes of products with harmful degree of alcohol; 4. Reduction of availability of products with harmful degree of alcohol; 5. Regulation of the associated publicity; 6. Brief preventive-persuasiveness intervention in the first level of attention; and 7. Random Tests for detection of alcoholic breath (breathalyzer). Results The independent measure with greater cost-effectiveness to avoid DALYs due to alcohol abuse was the increment of taxes, which is better when it reaches 50%. All increment of taxes avoids (with or without discount and adjustment by age) more than 1 50 000 DALYs per year. The increment of 50% surpasses even 300 000 DALYs per year (without adjustment neither discount). In contrast, none of the other interventions (with adjustment and discount) reaches 50 000 DALYs per year. Besides, the increments of taxes are always more economic than the interventions remainder. The extreme comparison of DALY avoided per year costs is among 50% taxes increment, which requires an investment of 567 Mexican pesos, and the brief intervention in the first level of attention, that implies an expense of 14,342 Mexican pesos. After taxes increment, effective independent interventions to reduce DALYs in Mexico include, in this order: reduction of the offering, integral prohibition of alcohol consumption publicity, brief intervention in the first level of attention, and the random test of alcoholic breath. Finally, the best integral strategy was a combination of the following measures: increment of taxes, greater proportion of people attended with brief interventions, control of publicity, and reduction of availability. Discussion In Mexico, as in many countries of the world, the increase of taxes was the most cost-effective intervention to reduce burden caused from abuse alcohol. This kind of interventions should consider the possible differential impacts according to the socioeconomical status of individuals or groups. Another related problem could be an increment of informal market. Therefore, it is necessary to complement the intervention with strategies directed at reducing the volume of alcoholic beverages that do not pay taxes. All other interventions (not taxes increment) were less cost-effective probably because they have considerably higher costs and smaller impact due their dispensation is eventual. Results of this exercise can have a positive impact among Mexican public policies on the field if the relevance of integral strategies is recognized, with political support, and having achieved a consensus of the population on the advantages of its orchestration.<hr/>Introducción Los análisis de costo-efectividad se sugieren como una herramienta esencial para gestionar e implementar políticas públicas en salud, pues permiten compararlas a fin de conocer cuál es la que obtiene mejor balance entre efectividad y viabilidad financiera. El objetivo del presente trabajo fue determinar el costo-efectividad de las intervenciones para prevenir y controlar el abuso de alcohol en México. Método Se utilizó la metodología WHO-CHOICE de la Organización Mundial de la Salud: un análisis de costo-efectividad generalizado (vs. particular) que toma en cuenta prácticamente los costos directos o tangibles (vs. los intangibles). El procedimiento implica la obtención de información de diversas fuentes, tanto de la enfermedad o problema en cuestión como de las intervenciones preventivas o terapéuticas a evaluar. Esta información se carga entonces para su análisis en un software o programa ad hoc. Se hace un descuento estándar de 3% anual para obtener y comparar el valor presente de los insumos, y se pondera la edad de los individuos, dando más peso a las etapas jóvenes. Finalmente, los resultados se plantean en términos de costo-efectividad de las intervenciones para reducir la carga de la enfermedad, definida en años vividos con discapacidad o disfunción (DALYs, por sus siglas en inglés: disability adjusted life-years). Las intervenciones que se evaluaron son: 1. Escenario actual: Impuestos al consumo de productos con grado nocivo de alcohol y pruebas aleatorias a automovilistas para detección de aliento alcohólico (alcoholímetro); 2. Incremento de 25% en los impuestos al consumo de productos con grado nocivo de alcohol; 3. Incremento de 50% en los impuestos al consumo de productos con grado nocivo de alcohol; 4. Reducción de la disponibilidad de productos con grado nocivo de alcohol (incrementar edad permitida del cliente, horario de venta, densidad de puntos de venta y corresponsabilidad del expendedor); 5. Regulación de la publicidad asociada al consumo de productos con grado nocivo de alcohol; 6. Intervención preventi-va-persuasiva breve en el primer nivel de atención; 7. Pruebas aleatorias a automovilistas para detección de aliento alcohólico. Resultados La medida independiente con mayor costo-efectividad para evitar DALYs debidos al abuso de alcohol fue el incremento de impuestos, más aún cuando llega a 50%. Todos los incrementos de impuestos evitan por sí solos (con o sin descuento y ajuste por edad) más de 150 000 DALYs por año. El incremento de 50% supera incluso los 300 000 (sin ajuste ni descuento). En cambio, ninguna de las otras intervenciones (con ajuste y descuento) llega a los 50 000. Además, los incrementos de impuestos son siempre más económicos que el resto de las intervenciones. La comparación extrema del costo por DALY evitado al año es entre el incremento de impuestos a 50%, que requiere una inversión de 567 pesos, y el consejo breve en el primer nivel de atención, que implica un gasto de hasta 14,342 pesos. Finalmente, la mejor estrategia integral fue la combinación de las siguientes medidas: incremento de impuestos, mayor proporción de personas atendidas con intervenciones breves, control de la publicidad y reducción de la disponibilidad de alcohol. Discusión Aunque el aumento de impuestos resultó, como en muchos países del mundo, la intervención aislada más costo-efectiva para reducir la carga que ocasiona el alcohol, deben tomarse en cuenta sus posibles impactos diferenciales en tanto el poder adquisitivo de los individuos o grupos y sobre el crecimiento del mercado de alcohol informal. Esto último sugiere la necesidad de acompañarle con estrategias dirigidas a reducir el volumen de bebidas alcohólicas que no pagan impuestos. El resto de las intervenciones fueron menos efectivas en tanto que tienen un impacto considerablemente menor cuando se dispensan de forma aislada, debido principalmente a sus altos costos. <![CDATA[<b>Hallucinations and delusions as anankastic representations</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500002&lng=pt&nrm=iso&tlng=pt The problem of representations Karl Jaspers introduced a distinction between perception and representation that presents a false dilemma when given a closer look. According to the renowned German psychopathologist, perceptions are corporeal and originate in the exterior objective space while representations are incorporeal and are derived from the interior subjective world. From his point of view, physicalness-imagination, 'exterior space-interior space', are absolute oppositions that permanently separate perception and representation by an abysm that allows no transition. For Amaral the confusion derives from the German word for perception «.wahrnehmung», composed by the noun wahr (truth) and by the verb nehmen (take as). In this manner and according to the language, anything that we consider true is necessarily treated as a perception. Nothing is more natural that German thinkers would loose, from such terminology, some flexibility in the evaluation of the phenomenon. Amaral has also reminded that Wundt, in 1874, already distinguished between sensation where stimuli not yet differentiated are perceived; perception, when stimuli organize themselves in a more or less defined manner, and apperception, where an attribution of meaning and a comprehension of the perceived scene or situation occurs. Crick and Koch propose aspects of great relevance to understand the so called Neural Correlates of the Conscience. They propose that the main function of the sensory cortex is to construct and use feature or specific qualities detectors such as those activated for orientation, movements, and face identification. Therefore, we may affirm that most of the sensory and motor activities are already made and available in the entire cerebral cortex, in the manner of what Changeux has called previous global representations. The conscious qualification process of the different sensory hues and their progressive complexity is a progressive feature, which in the phylogenetic evolution leads to the Homo sapiens sapiens. In fact, in the so called conscious media promoted by the thai amo-cortical activation that is performed in a task that requires effort and attention, we find spontaneously co-activated neural structures coordinated in time and space of the previous global representations type, which in turn generate other processes in the CNS. Hallucination and delusions: Anankastic representations? Since the times of Esquirol, the definition that a hallucination is a perception without object remained unaltered. Only recently, Alonso-Fernandez questioned Esquirol's scheme upon affirming «a hallucination is anything but a perception without object, because it is not a perception and because it does have an object. Contrary to the sensoperception activity that goes from the outside to the inside, a centripetal psychic function by excellence, the hallucination is produced upon objectivizing a psychic ¡mage providing it with sensoriality and subsequently projecting it to the exterior, shortly an objectivizing projection with, a clear centrifugal transit». In addition, today it is accepted that hallucinatory phenomena exist in sane individuals, related to some personality traits among which the imagination must be highlighted. The topic of delusion has been the object of the most varied reflections. In our case, we are interested in studying the phenomenon whereby the delusion installs itself in the center of the patient's life as a mineralized representation of the world and of himself, until structuring most of his behavior and relations, which we propose to call anankastic representation. To understand the phenomenon, we believe fundamental Llopis' idea that nature does not possess different laws to produce similar phenomena, therefore, both the delusion and hallucinations observed in the different clinical entities must obey the same pathogenetic mechanism, whereby «thought and perception disorders, in reality, are not different disorders qualitatively but only ways of expressing the different degrees of intensity in a disorder». From the psycho-physiological point of view, it must be underlined that what is activated in the hallucinatory phenomenon is a sensory network that carries a threatening signal for the patient, which is only possible because it is not under his superior control. Everything indicates that we are then dealing with representations that are presentified before a consciousness that does not recognize them as its own, because they have avoided the coincident mechanism of detection for afferent and re-entrysignals that support the conscious perception, according to the findings revealed by contemporary neurobiology. That is a critical aspect of the debate on the manner in which neurophysiology must approach the topic of representations, the information storage, the engrams, and the recognition of memories constituting a person. Simulation and supervision processes intervene in the different states of consciousness that make global access to the past, present and future possible. The individual is not only the receptor of stimuli derived from the environment, to which he responds from his brain with the innate guidelines registered in his genome, but he is also an agent maker of new realities and conducts. He is a poietic and autopoieticfador and because of that he has dignity. In the dialogue between genetic endowment and the environment and in the constitution of the epigenetic, consciousness and neuroplasticity are fundamental. In order for everything to function harmoniously, it would be necessary a balance of activity between the sensory cortex and the primary motor with the association areas scattered all over the cerebral cortex, and arranged from the prefrontal cortex. The constructs contained in previous representations must be reviewed in each opportunity and suffer some circumstantial arrangement or deep transformation, according to the case. We are dealing with a metacognition process through which the mind examines its own contents. Whenever a pathological situation alters this process, the constructs can become raw material for hallucinatory-delusional contents. The autopoiesis is interrupted and the mental dynamics is trapped by anankastic representations. Crick's zombies, Changeux's previous representation or Tellez's «timophanias», independent from the Self, imposed hallucinatorilly and automatically on a conscience that cannot differentiate them from reality, constitute therefore a symptomatic expression of what we have called mental illness as anánké.<hr/>El problema de las representaciones Karl Jaspers introdujo una diferenciación entre percepción y representación que, mejor vista, plantea un falso dilema. Según el gran psicopatólogo alemán las percepciones son corpóreas y se originan en el espacio objetivo exterior, mientras que las representaciones son incorpóreas y provienen del mundo subjetivo interior. Con arreglo a su criterio, corporeidad-imaginación, espacio exterior-espacio interior son oposiciones absolutas que separan siempre y sin transición la percepción y la representación por un abismo. El laureado neurofisiólogo Eric Kandel, al proponer un nuevo marco referencial para la psiquiatría, encuentra en la neurobiología una posibilidad cierta de aproximarse a la vida mental sana y enferma, en todo lo cual destaca los procesos inconscientes por los que se aloja y activa la memoria, estrechamente ligados a las representaciones. De la misma manera, son relevantes los trabajos de Crick y Koch sobre los correlatos neurales de la conciencia y sus zombie modes, que pueden ser pensados como reflejos corticales inconscientes estructurados como respuestas rápidas y estereotipadas, así como lo que Changeux ha denominado «representaciones globales previas». De hecho, en el denominado medio consciente, promovido por la activación tálamo-cortical, cuando se realiza una tarea que requiere esfuerzo y atención, encontramos coactivadas espontáneamente estructuras neuronales coordinadas en espacio y tiempo, del tipo de las representaciones globales previas que, a su vez, generan otros procesos en el SNC. Según Téllez, los arquetipos ¡unguianos son timofanías, es decir, representaciones de una actividad vital profunda que podrían ser conceptualmente asimilados a las representaciones globales previas y a los zombie modes de Crick y Koch. Los teóricos que estudian las relaciones entre caos y salud proponen, al contrario de lo que se ha venido pensando hasta ahora, que la salud tiene un alto ingrediente de incertidumbre, de la misma manera que una ausencia de variabilidad y caos fisiológico y comportamental conduce a una mineralización de las posibilidades de existir, tal y como ocurre en la mayoría de los trastornos mentales. Por lo tanto, las nuevas estrategias terapéuticas no deberían regularizar el comportamiento del enfermo en el nivel de su anánké, sino incrementar su repertorio de complejidad perdido transformando la psiquiatría en una verdadera ciencia de la libertad como lo proponía Henri Ey. La alucinación y el delirio: ¿representaciones anancásticas? El tema del delirio ha sido objeto de las más diversas reflexiones. En nuestro caso nos interesa estudiar el fenómeno por el cual el delirio llega a instalarse en el centro de la vida del enfermo, como una representación mineralizada del mundo y de sí mismo, hasta estructurar la mayor parte de su conducta y su vida de relaciones, lo que proponemos llamar representación anancástica. Para que todas las representaciones sean interpretadas armónicamente, es necesario un balance de actividad entre el cortex sensorial y motor primario con las áreas de asociación esparcidas por toda la corteza cerebral, al parecer concertadas desde el cortex prefrontal. Los constructos contenidos en las representaciones previas deben ser revisados en cada oportunidad y sufrir algún acomodo circunstancial o una transformación profunda, según sea el caso. Se trata de un proceso de metacognición por el cual la mente examina sus propios contenidos. Cuando alguna situación patológica altera ese proceso, los constructos pueden convertirse en materia prima para contenidos alucinatorios y delirantes. Quedan comprometidas la neuroplasticidad y la autopoiesis, y la dinámica mental es atrapada por estas representaciones anancásticas. Los zombis de Crick, las representaciones previas de Changeux o las timofanías de Téllez, independizados del Yo, impuestos alucinatoria y automáticamente en una conciencia que no puede diferenciarlos de la realidad, constituyen entonces una expresión sintomática de lo que hemos denominado la enfermedad mental como anánké. <![CDATA[<b>Comprehensive profile of candidates to the High Academic Performance Program (PAEA) of the Faculty of Medicine at Universidad Nacional Autónoma de México (UNAM)</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500003&lng=pt&nrm=iso&tlng=pt The importance to assess in a comprehensive way the cognitive, emotional, personal and social features of the students entering medical school is recognized nowadays in order to select from the candidates, not just those with high cognitive abilities, but also the ones with a vocation and interest in the study of this science. These are characteristics that should be specially sought among the students of high performance academic groups. In the Department of Medicine, as it is in some other departments at the Universidad Nacional Autónoma de México (UNAM), there is a special plan called High Academic Performance Program (PAEA), which aims to test innovative teaching models to generate health resources able to operate in special working conditions. Medicine students enrolled at the PAEA have a particular schedule which includes, in addition to the program established at the regular curriculum, some other specific activities, meaning greater demand for them. These special training includes activities such as: early introduction to research labs, based-problem learning, methodology workshops, introductory course in computing, and personalized assistance from academic tutors. It is because of these peculiar features, that, with this study, we aim to determine the profile of the students of the PAEA from the analysis and comparison of the candidates' characteristics. Materials and methods This was a comparative cross-sectional study that included all the first entry students at the Department of Medicine who applied to enter the selection process of the PAEA at the 2009-2010 period. These candidates were required to ask voluntarily to be included in the selection process to be part of PAEA, and to demonstrate at least a high school grade of 8.5, and to complete the assessment instruments. For this study, the assessment instruments used were: Minnesota Multiphasic Personality Inventory (MMPI-2), Differential Aptitude Test (DAT) sub-scale of abstract reasoning, and a semi-structured interview designed specifically for this evaluation. The variables considered for this research were: • Sociodemographic characteristics: All those features that define the economical, social and demographic situation of a person or population. • Academic background: All the information of studies and activities that the student has done throughout his/her school years. • Vocational features: Preferences, perceptions and attitudes of the student for his/her own autonomous choice of career or profession. • Personality traits: Generalized and focused mental systems that have the ability to convert external stimuli to guide different forms of behaviors. • Abstract reasoning: Mental process that allows people to solve logic problems, forecasting and planning. Data obtained from the instruments were analyzed with descriptive statistics, multiple linear regression, logistic regression, cluster analysis and factor analysis. Results The study included 194 candidates (100 of them were accepted to be included at the PAEA). In general, the studied population had a greater percentage of women (61.86%) and a mean age of 18.35 + 1.5 years old. Around a quarter of this population studied high school at Escuela Nacional Preparatoria (National High School), but it was observed that the highest percentage (20.1%) of students accepted to enter PAEA had the antecedent of being graduate from private high schools with high academic standards. This last finding is important since the candidates from these private schools are students who not only have access to a history of multiple academic and extracurricular activities, but they also come with certain academic stimulation, and so, it is expected that they have developed strategies to contend in competitive environments. The average grade of high school was lightly higher for the group of accepted students (9.27+0.41) than for those not accepted (9.13+0.47). Compared to those who were not accepted, more students in the group of accepted candidates were fluent in English (46.91%), French (1 4.43%) or other foreign language (3.61 %) besides Spanish. The personality profile obtained from the MMPI-2 was similar for both groups of candidates, accepted and not accepted. It was determined that accepted students were characterized by: having high energy and strength to achieve their goals, being sociable but with little commitment to the others, questioning the statu quo, being creative. However, within this group it was also observed that there was a tendency to manipulate other people to get what they wanted and that some of their behaviors may be governed by impulsivity. The group of candidates not accepted to the Program seemed to have the same personality features with greater energy, which could lead them into disarray. Characteristics such as social introversion and hypochondriasis have been aspects of interest in some previous studies. Both personality features have revealed significant long-term predictors, whether to have an adequate academic performance (associated to low levels of both social introversion and hypochondriasis) or to develop any psychopathology (related to high levels of social introversion and hypochondriasis). For this population, professional interests were directed towards the medical practice, while teaching was not considered as a priority interest (but it prevailed in the group of not accepted). Promotion of humanitarian aid discriminated those accepted candidates. At least 10% of the students in the group of accepted candidates said that they could see themselves having a successful future. The difference in interests within these students reflects distinct experiences in each group, and therefore dissimilar life projects that make them having diverse perspectives of present and future circumstances. The fact that the group of approved candidates has high motivation for success is consistent with their acceptance to be part of a group of high performance. However, it may be advisable to promote a training throughout their social awareness in order to enable them to have an overall performance of their profession. The best predictors of acceptance were: the rating of the overall review of knowledge (an exam that every first entry student does at the beginning of Medicine School) and the score of DAT's abstract reasoning, which correlated with r = 0.485. It is important to say that neither the grade of high school nor the age were good predictors to be accepted to PAEA. Conclusions Since PAEA seeks to select students with characteristics and skills that enable them to function in the field of medicine under a high rate of academic achievement, it is expected that, as it was confirmed in this research, accepted students where those who had greater cognitive abilities, who were fluent in other languages, with interest focused on successful clinical practice and research, and with less concern about socio-economical aspects of their environment. However, there are still many questions regarding the defining characteristics of this population and the way these features will impact their education. It is necessary to continue characterizing and studying the groups of students entering PAEA, and follow up their outcome in order to determine if the evaluated aspects have an influence on their academic performance during medical school.<hr/>En la Facultad de Medicina, como en algunas otras de la Universidad Nacional Autónoma de México, existe un Programa de Alta Exigencia Académica (PAEA), el cual busca probar métodos de enseñanza novedosos para formar recursos capaces de desarrollarse en condiciones especiales de trabajo. Esto se lleva a cabo por medio de un programa en que el alumno lleva, además de las actividades regulares establecidas en el currículum de la carrera, algunas otras planeadas específicamente para estos grupos y que demandan mayores exigencias para los estudiantes que forman parte de ellos. Dadas estas características del PAEA en la Facultad de Medicina, es prioritaria una evaluación integral de los candidatos que formarán parte del programa, la cual debe incluir aspectos cognoscitivos, emocionales, personales y sociales. Por ello, el objetivo de este estudio fue establecer el perfil de los alumnos del PAEA a partir del análisis y la comparación de las características de la población de candidatos que se postularon para ingresar a este programa durante la promoción 2009-2010. Material y métodos Estudio transversal comparativo en el cual se incluyó a todos aquellos estudiantes de primer ingreso (ciclo 2009-2010) que solicitaron de manera voluntaria ingresar al proceso de selección del PAEA, que tuvieron por lo menos 8.5 de promedio en el bachillerato y que completaron los instrumentos de evaluación. Se aplicaron: el Inventario Multifásico de la Personalidad Minnesota-2 (MMPI-2), la subescala de razonamiento abstracto del Test de Aptitudes Diferenciales (DAT), y una entrevista semiestructurada diseñada expresamente para esta evaluación. Los datos obtenidos se manejaron con estadísticos descriptivos, regresión lineal múltiple, regresión logística, análisis de clusters y análisis factorial. Resultados Se incluyó a 194 aspirantes, de los cuales fueron aceptados 100, con un predominio en la población femenina (61.86%) y una media de edad de 1 8.35 ± 1.5. Una cuarta parte de la población estudiada provenía de las Escuelas Nacionales Preparatorias, pero el mayor porcentaje de aceptación (20.1%) para ingresar al PAEA se observó entre los alumnos egresados de escuelas preparatorias privadas de alto nivel académico. El perfil de personalidad obtenido por medio del MMPI-2 fue similar para los candidatos aceptados y los no aceptados. Los alumnos aceptados para ingresar al PAEA se caracterizaron por: presentar una gran energía y consolidar sus metas, ser sociables pero con poco compromiso con los demás, cuestionar el status quo y ser creativos; no obstante, se observó una tendencia a manipular a los demás para conseguir sus fines. Algunas de sus conductas pueden estar regidas por impulsividad. Los alumnos no aceptados presentaron estas características con una mayor energía que pudiera llevarlos a la desorganización. Los intereses profesionales se dirigieron hacia la práctica médica. Aunque la docencia no fue considerada como un interés, predominó entre los no aceptados, mientras que la promoción de ayuda humanitaria discriminó a los aceptados. Los mejores predictores de la aceptación fueron la calificación del examen general de conocimientos y el razonamiento abstracto, los cuales se correlacionaron con r=0.485. Ni la edad, ni el promedio de bachillerato fueron buenos predictores en cuanto a la aceptación para entrar al PAEA. Conclusiones Dado que el PAEA busca seleccionar alumnos con características y habilidades que les permitan desempeñarse en el campo de la Medicina con un ritmo de alto rendimiento académico, resulta esperable que, tal como se corroboró en esta investigación, se aceptaran alumnos con una mayor competencia cognoscitiva, con dominio de otras lenguas, con intereses centrados en la práctica clínica exitosa y en la investigación, y con menor preocupación por aspectos socioeconómicos de su entorno. Sin embargo, será preciso continuar perfilando y estudiando a los estudiantes de este programa con el fin de determinar aquellos rasgos que influyen en su desempeño durante la licenciatura. <![CDATA[<b>Associated factors to the search and use of health services</b>: <b>from the psychosocial to the socio-economic model</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500004&lng=pt&nrm=iso&tlng=pt This article includes the results of a multi-level conceptual approach review, considering four models of analysis, delving into the determinants and the explanatory factors in the process of search and use of health services. Such models are: psychosocial, epidemiological, sociological, and socio-economic. The implications, determinants, and characteristics of utilization of health care services have been subject to scrutiny since the eighties. Research on this matter has not been independent of the process of reform, which has been carried out simultaneously in virtually every country in the world. In fact, establishing adequate health services for patients who need them most has become a generally accepted priority. For the purpose of this study, and as a preamble to understanding the process of search and use of health services, the concept of need, along with its applications in the different models of service use, must be defined. In the literature, there are four types of need: a) normative need, that which is expert-defined as such in a given situation, b) felt need, which corresponds to a perceived lack of something beneficial to the individual, c) expressed need, one not only experienced, but also articulated by the individual, and d) comparative need, i.e. a standard that meets the same characteristics of another receiving certain coverage or service. This paper will refer to the expressed need, which may or may not correspond exactly to the use of health care services. Along the same lines, the concept of demand, applied from an economic perspective, will be utilized as a synonym for use. The implementation of reform processes and the evaluation of the possible implications of such reforms require extensive knowledge regarding the determinants of use of health care services. A main determinant can be identified, for example, when an individual uses such services, sometimes repeatedly, because he is in a situation of need (experienced), understood as the perception of discomfort or illness. There are certain biological differences (i.e. sex and age) that might explain some of the variations observed in the relationship between situations of need and use. However, could there be other reasons that would lead to use? If so, this situation might create unnecessary extra work for professional health care providers preventing them from engaging the real needs of the population served; on the other hand, if there are any other motives (besides the absence of necessity) causing an individual, or group of individuals, not to meet his care needs, he may be at risk. It is widely known that not all health problems are reported to physicians by patients at the time of consultation. Also, there are great numbers of single users who are responsible for the utilization of a large portion of consultations intended for that population, taking advantage and, occasionally, using health services without having, from a medical standpoint, a clear justification to do so. These examples are extremes that can be observed as patterns of use that are determined by the perceived need for health and a long list of factors described from different disciplinary perspectives. Analyzing the search and use of health services implies studying availability and accessibility to them. Although the measurement of these variables is not exact, it is used in most studies. When considering use by socio-economic group accessibility, the fairness of the system in question is also evaluated. This is highly relevant because problems of use of services are related to health equity and accessibility, two challenges currently being addressed by a substantive reform of the health systems in most countries of the world; particularly in Latin America, and more so in Mexico. Thus, this paper intends to address, through a review of different theoretical models, factors affecting the search and use of health services. It assumes that the central premise in the context of health sector reforms in Latin America, especially in Mexico, is that the health service users have come to occupy a leading role in establishing the health needs addressed by care systems. Indeed, the main issues of structural adjustment in health systems are related to setting health needs according to epidemiological changes, changes in perception of diseases, and changes in the variables of equity, efficiency, coverage, and accessibility to health systems for different population groups. From this new perspective, the health systems, in turn, propose relevant changes in the interaction between the two main social actors within this reform process: first, the behavior of suppliers (any institution that provides health services to the population), and second, the behavior and perceptions of consumers (population using health services demanded from a particular institution). The path converges when both social actors represent the process of seeking and obtaining medical care, as determined by a number of variables and constraints addressed in this article through different conceptual approaches, i.e. whenever the explanatory conceptual model is used, the process of medical care is primarily conceived as two chains of activities and events where participants are parallel -the care- giver on the one hand, and the client or user of health services on the other. In an extended approach, use and its determinants have much to do with the study of accessibility, coverage, and equity in health. Some authors claim that, under this approach, the study of accessibility and coverage in health are made identical to the determinants of service utilization. This wider vision includes various aspects, considering use as a schematic sequence of events from the time the need for medical attention arises until it initiates/is followed by the use of medical services. Throughout this process, psychosocial and epidemiological determinants of care are identified, including seeking process aspects such as health-related beliefs, confidence in the health care system, disease frequency, pain tolerance, and presence of disability. This schematic succession of events is precisely what has allowed the study of health service use to exhibit different approaches, which in turn has led to the creation of various psychosocial and epidemiological models that have attempted to explain why the population does not use health services. From an economic perspective, the literature on health service utilization mainly considers two approaches: the traditional approach and the managerial approach. These provide different but complementary explanations regarding demand and investment in health services. The traditional approach to demand for health services is based on consumer theory, where demand for medical services is mainly determined by the patient but conditioned by the health system. Within this emerging model, demand for health services is the result of a problem of inter-temporal utility maximization of the patient, and considered a function in the production of health. The managerial approach, related to human capital theory, considers information asymmetries between doctor and patient regarding the type and quantity of necessary medical treatment. In this context, the decision making process can be divided into two parts: first, patients initially choose whether or not to seek treatment, and then, once the patient begins treatment, the physician determines the number of visits and use of services for tracking, monitoring, and controlling the damage that initially triggered the stages.<hr/>El presente artículo incluye los resultados de una revisión y reflexión sobre diferentes niveles de aproximación conceptual que plantean cuatro modelos de análisis para el estudio de los condicionantes, determinantes y factores explicativos del proceso de búsqueda y utilización de servicios de salud. Dichos modelos son: el psicosocial, el epidemiológico, el sociológico y el socioeconómico. Se parte de la premisa central de que en el contexto de reformas del sector salud en países de América Latina, y particularmente en México, los usuarios de servicios de salud pasan a ocupar un rol preponderante en el establecimiento de las necesidades de salud que deberán responder los sistemas de atención médica. En efecto, los principales hilos conductores y de ajuste estructural de los sistemas de salud lo constituyen los cambios en el establecimiento de necesidades de salud de acuerdo con cambios epidemiológicos, cambios en la percepción de daños a la salud, así como cambios en las variables de equidad, eficiencia, cobertura y accesibilidad de los sistemas de salud para diferentes grupos poblacionales. Desde esta nueva perspectiva, los cambios del sistema de salud proponen a su vez cambios relevantes en la interacción entre los dos principales actores sociales de este proceso de reforma: por un lado, el comportamiento de los proveedores (toda institución que provee servicios de salud a la población) y, por otro, el comportamiento y percepción de los usuarios (población que busca y solicita servicios de salud a determinada institución). El camino de ambos actores sociales converge en lo que representa el proceso de búsqueda y obtención de la atención médica, determinado por una serie de variables y condicionantes que se abordan en este artículo, desde diferentes enfoques conceptuales. En un enfoque ampliado, la utilización y sus determinantes tienen mucho que ver con el estudio de la accesibilidad, la cobertura y la equidad en salud; es más, algunos autores afirman que bajo este enfoque, el estudio de la accesibilidad y cobertura en salud se hace idéntico al de los determinantes de la utilización de los servicios. Este enfoque ampliado comprende diversos aspectos, considerando la utilización como una sucesión esquemática de acontecimientos desde el momento en que surge la necesidad de atención médica hasta el momento en que se inicia o se continúa la utilización de servicios médicos. A lo largo de este proceso se identifican como determinantes psicosociales, sociales y epidemiológicos del proceso de búsqueda de atención aspectos que incluyen creencias relativas a la salud, la confianza en el sistema de atención médica, la frecuencia de la enfermedad, la tolerancia al dolor y la presencia de discapacidad. Esta sucesión de acontecimientos es precisamente lo que ha permitido el estudio del uso de servicios de salud desde diferentes enfoques, dando lugar al diseño de diversos modelos psicosociales, sociales y epidemiológicos, que han intentado explicar el motivo por el cual la población hace uso o no de los servicios de salud. Por otra parte, desde una perspectiva económica, la literatura sobre utilización de servicios de salud considera principalmente dos enfoques: el enfoque tradicional y el enfoque gerencial. Estos enfoques proveen explicaciones diferentes pero complementarias sobre la demanda y la inversión en servicios de salud. El enfoque tradicional de la demanda por servicios de salud se basa en la teoría del consumidor. Bajo este enfoque, la demanda de servicios médicos está determinada principalmente por el paciente pero condicionada por el sistema de salud. El enfoque gerencial, relacionado con la teoría de capital humano, considera las asimetrías de información entre el médico y el paciente en relación con el tipo y cantidad de tratamiento médico necesario. En este contexto, el proceso de toma de decisiones puede dividirse en dos partes. En la primera, el paciente elige inicialmente si busca tratamiento o no y en la segunda, una vez que el paciente empezó el tratamiento, el médico determina el número de visitas y uso de servicios para seguimiento, monitoreo y control del daño que inicialmente desencadenó las fases del proceso. Todas y cada una de las fases descritas son abordadas desde diferentes perspectivas en este artículo, donde se describen los condicionantes y/o determinantes del proceso de búsqueda y utilización de los servicios de salud y se hace un análisis cruzado con cada modelo revisado mediante una matriz de contingencia. Finalmente, el análisis integral de los modelos estudiados se propone como punto de partida para avanzar en un modelo que permita, de manera transdisciplinaria, encontrar la explicación más acertada de los determinantes y condicionantes del proceso de búsqueda y uso de servicios de salud. <![CDATA[<b>Emotional support and experiences of HIV</b>: <b>impact on Mexican men and women from a gender perspective</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500005&lng=pt&nrm=iso&tlng=pt Introduction The Mexican HIV epidemic is characterized by affecting a greater number of men than women, with the bulk of infections occurring among men who have sex with men, and women being exposed primarily through their stable male partner. Since the beginning of the epidemic, the proportion of women with HIV has increased and the most recent estimates indicate that one out of every four Mexicans with HIV is a woman. Analyzing the emotional and psychological impact of HIV from a gender perspective highlights that while there are similarities in how Mexican men and women experience the HIV diagnosis and adjust to life with HIV, there are also important differences. This study sought to understand how gender influences the type of material and emotional support received by Mexican men and women with HIV. In this article, we discuss the ramifications of gender in two specific situations: first, the reaction to the HIVdiagnosis and related perceptions about how infection occurred; and second, the process of learning to live with the virus. We argue that social constructions of gender are determinant for shaping personal experiences, expectations and roles, as well as for creating differential access to the material, social and symbolic resources necessary for personal development among people with HIV. Dominant Mexican gender norms make men and women more vulnerable to HIV infection and also limit access to resources for improving quality of life post-diagnosis. Methods This article draws on in-depth semi-structured interviews with 20 adult men and 20 adult women with HIV from Morelos, Guerrero, Mexico City and Mexico State carried out during 2003-2004. Inclusion criteria for participation in the study were having known the HIV-diagnosis for more than a year, self-defining as heterosexual, and being ambulatory. The authors completed an inductive analysis, drawing on the basic elements of Grounded Theory proposed by Glaser and Straus in which data collection and analysis mutually inform the emergence of central themes. The research protocol was approved by the Research, Biosecurity, and Ethics review boards of the Mexican National Institute of Public Health. All research participants completed written informed consent. Results and discussion While all of the people with HIV interviewed lived an emotional process fraught with sadness and uncertainty as they assimilated the HIV diagnosis, most men «suspected» that they could be HIV-positive before the diagnosis while for most women the HIV diagnosis was «unimaginable». This finding relates directly to gendered constructions of sexuality in Mexico. Congruent with epidemiological findings, most of our women research participants were infected in the context of a stable relationship where they had been sexually monogamous. Consequently, they experienced the diagnosis as a betrayal which shook the foundations of their identity, their relationship and sometimes provoked critical reflection on the dominant social narratives about the rewards of being a «good woman». For other women, the threat recognition of their male partner's sexual infidelity posed to the relationship and to their sense of self made continued avoidance of the evidence preferable. The dominant narratives of romantic love and fidelity which have been inculcated in Mexican women contribute to their vulnerability to HIV infection by encouraging them to deny, or at least remain silent about men's extramarital sexual relationships. Social constructions of sexuality also put men at risk of HIV infection. Men had internalized cultural messages about «how to be men»which included having multiplesexual partners and using alcohol and drugs. Among our research participants, the combination of alcohol or drugs with sex was frequently the context for the highest risk behaviour for acquiring HIV, such as unprotected sex between men. Many men described the HIVdiagnosis as confirming their fears about being infected or perceived the diagnosis as a logical outcome of their «voracious» and socially legitimated sexual risk-taking behaviour and substance use. In reflecting on how gender norms had contributed to their HIV infection, men expressed regret and confusion, and when they had exposed their female partner, guilt about harming an «innocent» and «defenseless» woman. Transformation of dominant constructions of heterosexuality and an ethics of mutual honesty and responsibility in the context of greater equality between men and women is clearly needed to prevent new HIV infections and to support resolution of negative feelings about the diagnosis and route of infection. Similarly, a gender divide was identified in the realm of social and emotional support. Women continued to «care for others» after the diagnosis, providing emotional support to their male partner and family, and if they were widowed or separated, assuming the breadwinner role. Admitting feelings of sadness or pain and asking for help are culturally constructed as feminine attributes, and doing so challenges men's socially constructed gender role. However, the fact that men are not socialized to solicit emotional and practical support does not imply that it is not available. The gendered social structure is enacted in such a way that women provide support without men asking. Men with HIV continued to be cared for by women post-diagnosis; if men were widowed or separated, female friends or family members provided practical and emotional support. Gendered expectations about the respective roles of men and women also limited some men's access to social support because of the belief that they could'not begin a new affective relationship because they had «nothing to offer» without economic earning power. For both men and women, learning to live with HIV was a process. In general, the more time had passed since the diagnosis the more likely it was for people with HIV to receive specialized medical care, have access to accurate information about HIV disease, and to report social support from family, friends and other people with HIV. Peer relationships in support groups and civil society networks were a catalyst for personal transformation and improving quality of life post-diagnosis. Men and women who expressed more traditional gender roles experienced higher barriers to support group participation. The men who most fervently defended their heterosexual identity were uncomfortable with the predominantly homosexual composition of support groups. Women who confined themselves to the homemaker role and did not participate in support groups continued to perceive themselves as victims, were treated as dependents within their social networks, and were less able to overcome negative feelings associated with the diagnosis. Other women with HIV used support groups as a resource for reconstructing their lives and social networks, and some became advocates for the rights of women and people with HIV.<hr/>Introducción Aun cuando las cifras de infección en México son mayores entre hombres que en mujeres (71.5 y 28.5% respectivamente), el análisis de la epidemia desde un enfoque de género arroja luz sobre posibles similitudes y diferencias en la experiencia de vivir con VIH/SIDA para ambos. El interés del presente estudio se centró en identificar diferencias de género en el soporte emocional y social proveniente de las redes de apoyo de estas personas. En este artículo nos referiremos a dos situaciones particulares: primero, la percepción de la manera en que se adquirió el virus, lo cual sirve como ejemplo de la construcción social del género que impacto en las emociones y vivencias de la enfermedad según se sea mujer u hombre, ysegundo, el proceso de transformación por el que las personas con VIH reorganizan sus necesidades y circunstancias después del diagnóstico. Material y métodos Se realizaron entrevistas en profundidad a personas que viven con VIH/SIDA (20 hombres y 20 mujeres), en estado ambulatorio y con más de un año de diagnóstico, en cuatro Estados de la República Mexicana (Morelos, Guerrero, Estado de México y el Distrito Federal), todas ellas autodefinidas como heterosexuales. La información se analizó de manera inductiva usando elementos de la teoría fundamentada. Con base en una tipología de códigos y definiciones creada a partir de la guía de entrevista y reconformada a lo largo del proceso de codificación, se organizó la información por temas emergentes. Resultados La mayor parte de los hombres tendió a recibir el diagnóstico de VIH como algo «sospechado», mientras que la mayoría de las mujeres como «inimaginable», lo cual se relaciona con normas de género que limitan la capacidad de las personas para actuar frente al VIH. Mientras que la mayoría de las mujeres informó tener menos parejas sexuales y más estables a lo largo de su vida, los hombres reportaron mayor número de encuentros sexuales ocasionales, con hombres o mujeres, incluso cuando vivían con una pareja estable. Aunque en algunos casos no había certeza sobre quién transmitió el virus a quién, en su mayoría los hombres asumían la responsabilidad de haber infectado a sus parejas. Lo anterior desencadenaba procesos diferenciados de manejo de la información acerca del diagnóstico, de sentimientos de culpa o resentimiento, así como del estado emocional con que unos y otras manejaban su nueva condición de seropositivos(as). El contacto con redes sociales alternativas, que permiten re-significar las normas sociales y estructuras rígidas de género, puede tener efectos positivos para hombres y mujeres con VIH. La participación en grupos de autoapoyo y la oportunidad de relacionarse con otras personas que viven con VIH/SI DA constituyó para hombres y mujeres la posibilidad de enfrentar la enfermedad deforma menos solitaria, de acceder a información veraz, a mejores condiciones de vida y de atención en salud. Es decir, su participación en grupos posibilitó tomar la enfermedad en sus manos dándoles la oportunidad de modificar sus relaciones personales y estructuras de género. Discusión Los efectos positivos así como las limitaciones de los grupos y redes sociales de apoyo a hombres y mujeres con VIH, muestran la necesidad de establecer programas y políticas de prevención y atención bajo una perspectiva de género y de derechos humanos, que entre otros beneficios ayude a incrementar la calidad de vida de estas personas. <![CDATA[<b>Smoking prevention programs for girls</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500006&lng=pt&nrm=iso&tlng=pt In recent years, the number of women who use tobacco has increased rapidly. Among youngsters, gender gap is closing, and the proportion of girls who smoke is already very similar to that of boys, with the added complication that the girls are more vulnerable to addiction, and tobacco use has severe consequences for their health and the well-being of their future children. The key to facing tobacco epidemic is prevention by strengthening protective factors and reducing risk factors that lead to smoking onset. School environment is the most valuable resource for anti-smoking programs. These efforts are commonly focused on elementary and secondary students because experimentation with tobacco and adoption of smoking behavior occur at this stage. There are three intervention models in schools: 1. Information model (or rational), 2. Social skills model (or affective), and 3. Social influence model, which emphasizes social environment as a critical factor in tobacco use. In this model the children are informed about the immediate negative effects of smoking (unfavorable effects on appearance, economic costs and social consequences such as rejection by others). The model also conveys a positive image of non-smokers as rational people, and a negative one of a smoker as someone vulnerable to advertising tricks. It uses the peer group for showing resistance to pressure and how to adopt and to maintain the decision not to smoke, and it teaches how to identify influences from tobacco advertising, peers and family. The social influence programs tend to be the most effective strategy for achieving at least some delay in onset of tobacco use. It is necessary to develop appropriate programs for each age and for a specific gender. Recently, researchers have begun using programs based on computer systems and Internet to prevent teen smoking. The aim of this study was to design, implement and evaluate two different types of tobacco prevention programs, tailored specifically for teenage girls. The programs were computer games and an interactive workshop, as well as the combination of both of them (games plus workshop). It was suggested that in treatment groups versus control group, smoking susceptibility scores (i.e., lack of a firm commitment to not smoke) would be lower in post test. It was also hypothesized that the games plus workshop group would affect the scores of the associated variables with susceptibility, and that changes would remain in the follow-up. Material and methods 537 student girls in the three grades of secondary school were asked to answer the Smoking Susceptibility Scale. Out of this group, 160 girls that obtained the highest scores were selected, because they were considered at risk of becoming regular smokers. Six variables related with smoking susceptibility were also measured: Belief in the addictive property of tobacco, beliefs in smoking benefits, empathy with smoking victims, negative attitudes toward tobacco industry, skills rejecting social pressure to smoke, and identification of diseases associated with smoking in women. The Smoking Susceptibility Scale was applied at three moments of the measurement: A pretest (one week before programs starting), a post test (the last day of the program or programs), and a follow-up (four months after implementing the post test). In the last two occasions, the instruments of variables related with susceptibility were also applied. The two types of prevention programs (computer games and interactive workshop) were based on the social influence model. The purpose of the games was that the girls acquire skills to recognize and resist social pressures to smoke exerted by both the tobacco industry through advertising strategies, and their peers. The interactive workshop was designed according to the strategies of anti-smoking messages that have proved to be effective in order to prevent smoking; the immediate negative consequences suffered by smokers and the physical and psychological vulnerability of women produced by smoking were also highlighted. A mixed 4 inter-groups X 3 intra-groups design was applied (4 treatments: Computer games, interactive workshop, games plus workshop, control, X 3 measurement times: Pretest, post test, follow-up). The 160 participants were randomly assigned to one of the four treatment groups. The study consisted of four phases: pre test, treatment (one week later), post test (on completion of program implementation) and follow-up (four months after the post test). Results There was an immediate effect of the three treatments on the smoking susceptibility by contrasting pre test versus post test, but games plus workshop group had more effect than games or workshop ones. When comparing post test and follow-up measurements in the games plus workshop group versus the control group, it was found that smoking susceptibility scores of the treatment group stayed unchanged. For related variables, the girls who participated in the games plus workshop group had higher scores than the control group in the belief of tobacco addictive property, in empathy with smoking victims, in the negative attitude toward the tobacco industry, in the refusal skills towards social pressure to smoke, and in the identification of diseases associated with smoking in women, and lower scores on beliefs in the benefits of smoking (attractive appearance, emotional well-being, popularity and social acceptance). At the follow-up, it was observed that attitudes toward tobacco companies became even more negative and that participants identified more diseases caused by smoking in women than in the post test, i.e., the treatment effect was strengthened. Discussion The main guideline in the construction of smoking behavior prevention programs evaluated in this study was its focus on adolescent girls. Furthermore, they were only addressed to those adolescents with high scores on smoking susceptibility, due to the intention of using the available resources more efficiently. Another criterion taken into a count in order to build these programs was the shortness of the intervention. The results showed that smoking susceptibility on the participants of each one of the three treatment groups decreased from the pre test to the post test, but the decline was even greater in the games plus workshop group. The smoking susceptibility of the games plus workshop group remained low in the follow-up after four months of its implementation, which did not occur with the workshop or games groups alone. It appears that the more elements used in the prevention programs the greater their impact will be. Compared with the control group, the majority of variables related with smoking susceptibility were affected by the games plus workshop treatment. In conclusion, the combination of preventive programs for smoking addiction constructed in this study specifically for girls with the implementation of psychosocial principles and the use of computer technology decreased the smoking susceptibility on participants, as well as most of the related variables. Moreover, their effects persisted at least for a period of four months. Computer games, which were of interest to participants, could be easily installed on computer rooms of secondary schools, and even uploaded in the Internet, and its effects could be enhanced by an interactive workshop, which promotes interpersonal contact and discussion of false beliefs regarding tobacco use that girls support. The girls at risk who change their smoking susceptibility as a result of their participation in these smoking prevention programs will avoid the severe consequences of using tobacco and will gain years of healthy life for themselves and their descendants.<hr/>El consumo de tabaco en las mujeres se ha incrementado aceleradamente. Entre los adolescentes, la brecha de género se está estrechando, ya que el porcentaje de fumadoras es ya muy similar al de los varones, con el agravante de que ellas son más vulnerables a la adicción al tabaco y su consumo tiene serias consecuencias para su salud y la de sus futuros hijos. La principal alternativa para enfrentar la epidemia de tabaquismo es la prevención. Existen básicamente tres modelos de intervención antitabaco en las escuelas: modelo de información, modelo de habilidades sociales y modelo de influencia social, el cual ha mostrado ser el más efectivo para lograr, al menos, retrasar el inicio del consumo. Se ha señalado que es necesario desarrollar programas adecuados específicos para cada edad y género. El propósito de la presente investigación fue construir, aplicar y evaluar dos diferentes tipos de programas de prevención del tabaquismo (juegos de computadora y taller interactivo) y la combinación de ambos (¡uegos+taller), dirigidos específicamente a mujeres adolescentes. Material y métodos De las 537 mujeres estudiantes de secundaria que contestaron la Escala de Susceptibilidad Tabáquica, las 160 adolescentes que obtuvieron los puntajes más altos fueron asignadas aleatoriamente a uno de cuatro grupos de tratamiento: Juegos de computadora, Taller interactivo, Juegos+taller y Control. Los programas se desarrollaron con base en el modelo de influencia social. El estudio constó de cuatro fases: premedición, tratamiento, pos-medición y seguimiento (cuatro meses después). Se evaluaron además seis variables precurrentes de la susceptibilidad tabáquica: creencia en la propiedad adictiva del tabaco, creencias en los beneficios de fumar, empatia hacia las víctimas del tabaco, actitud negativa hacia las tabacaleras, habilidades de rechazo ante la presión social para fumar e identificación de enfermedades asociadas con el tabaco en las mujeres. Resultados La susceptibilidad tabáquica de las participantes en los tres grupos de tratamiento disminuyó significativamente de la premedición a la post-medición, pero los efectos persistieron en el seguimiento sólo en el grupo de Juegos+taller. Respecto de las variables precurrentes, quienes participaron en el grupo Juegos+taller obtuvieron puntajes más altos que las del grupo control en la creencia en la propiedad adictiva del tabaco, en la empatia hacia las víctimas del tabaco, en la actitud negativa hacia las tabacaleras, en las habilidades de rechazo a la presión social para fumar y en la identificación de las enfermedades asociadas con el tabaco en las mujeres, y menores puntajes en las creencias en los beneficios de fumar (apariencia atractiva, bienestar emocional, popularidad y aceptación social). En el seguimiento se observó que las actitudes hacia las tabacaleras se hicieron aún más negativas y las participantes señalaron más enfermedades causadas por el tabaco en las mujeres, que en la posmedición, es decir, se reforzó el efecto del tratamiento. Discusión La combinación de los programas preventivos de la adicción al tabaco para mujeres adolescentes construidos en este estudio con la aplicación de principios psicosociales y la utilización de tecnología computacional, disminuyeron la susceptibilidad tabáquica de las participantes, así como la mayoría de las variables precurrentes. Además, sus efectos persistieron durante un periodo de cuatro meses. Los programas podrían aplicarse fácilmente en el ámbito escolar: los juegos de computadora podrían instalarse en los salones de cómputo o colocarse en Internet, y su efecto se reforzaría con el taller interactivo, el cual es de intervención breve y propicia el contacto interpersonal y la discusión de las creencias falsas respecto del consumo de tabaco que sostienen las adolescentes. Las chicas en riesgo tabáquico que cambien su susceptibilidad como consecuencia de su participación en estos programas evitarán las serias consecuencias del consumo de tabaco y ganarán años de vida sana para ellas y sus descendientes. <![CDATA[<b>Retention rates and potential predictors in a longitudinal randomized control trial to prevent postpartum depression</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500007&lng=pt&nrm=iso&tlng=pt Perinatal depression is increasingly recognized as a significant public mental health problem; consequently, there is a major interest in developing strategies to prevent postpartum depression that may help reduce its detrimental consequences. However, the unique experiences associated with the perinatal period make it more difficult to recruit participants at this stage and to retain them over time when assessing prevention interventions. The aim of the study is to examine retention rates and predictors of retention in a longitudinal, randomized controlled trial (RCT) to prevent postnatal depression. Method Participants: Pregnant women (N = 377) at risk of depression were randomized to intervention or usual care condition and assessed during pregnancy and at 6 weeks and 4-6 months postpartum. Intervention: The intervention was designed by modifying a previously evaluated one and includes information on normal pregnancy and the postpartum period, from psychoanalytic and risk factors perspectives. It attempts to reduce depression levels by increasing positive thinking and pleasant activities, improving self-esteem, increasing self-care, learning skills to strengthen social support, and exploring unrealistic expectations about pregnancy and motherhood. It is delivered in eight two-hour weekly group sessions during pregnancy. Measures: Depressive symptoms were measured using the second edition of the Beck Depression Inventory (BDI-II); anxiety symptoms with the corresponding subscale of the Hopkins Symptoms Checklist (SCL-90) and social support with the Social Support Apgar (SSA). A short form of 12 items representing potential stressors was used as a measurement of stressful life events and the Abbreviated Version of the Dyadic Adjustment Scale (A-DAS) measured partner relationship. Results Retention rates -defined in three ways- were: (1) Total retention (percentage of participants completing the 4-6 month postpartum interview) was 41.7% (31.2% intervention and 61.4% control); (2) Retention from randomization to (a) completion of initial evaluation and attendance of > 1 intervention sessions was 42.4%; and (b) completion of initial evaluation (control) was 82.2%; and (3) Follow-up retention: (a) intervention participants attending > 1 sessions that completed the intervention as well as the 4-6 months postpartum interview was 73.5%; and (b) control participants assesses in this period was 66.6%. For those who came to at least one intervention session 83% completed the intervention. The predictors of total retention were: being single, more educated, and poor partner relationship quality. For the intervention condition, predictors of (a) retention from randomization to attendance to > 1 sessions were anxiety and stressful life events, and (b) for follow-up retention was being employed. Conclusions In the present study, retention of participants was even lower than what has been found in similar interventions. However, attendance rates of the course, once the participants had attended one session, were very good. In terms of predictors of retention, women at high risk of depression (single, with poor partner quality relationship, more stressful life events and high anxiety) were more committed to participating in the study. Consequently, in order to increase retention rates, future interventions should target women that present such risk factors. Nevertheless, those with low educational attainment and homemakers, who are a vulnerable group, were difficult to retain and thus remain a challenge in postpartum depression prevention studies. We conclude that rates and predictors of retention differed depending on points of measurement, suggesting different strategies to optimize participation.<hr/>La depresión perinatal cobra cada día mayor reconocimiento como un problema importante de salud mental pública; en consecuencia, ha crecido el interés por desarrollar estrategias para prevenir la depresión posparto, que lleven a evitar sus consecuencias adversas. Sin embargo, las peculiaridades del periodo perinatal dificultan tanto el reclutamiento como la retención de esta población a lo largo del tiempo, cuando se evalúan intervenciones preventivas. El objetivo del estudio es examinar las tasas de retención y las variables que predicen las mismas en un estudio longitudinal aleatorio controlado (EAC) para prevenir la depresión posparto. Método Participantes: Trescientas setenta y siete embarazadas que mostraron riesgo de depresión fueron aleatorizadas a grupos de intervención y control y evaluadas durante el embarazo y a las 6 semanas y a los 4-6 meses después del parto. La muestra se tomó de salas de espera de tres instituciones que proporcionan atención prenatal. Intervención: La intervención se desarrolló a partir de modificar una anterior dirigida a mujeres con depresión para incluir información sobre el embarazo y puerperio normales desde una perspectiva psicoanalítica y de factores de riesgo de depresión posparto. Pretende reducir la depresión al reforzar los pensamientos positivos y las actividades agradables, mejorar la autoestima y el autocuidado, desarrollar habilidades que fortalezcan el apoyo social y explorar las expectativas poco realistas sobre el embarazo y la maternidad. Se imparte en ocho sesiones grupales durante el embarazo, dos horas por semana. Instrumentos: Los síntomas de depresión se midieron con la segunda versión del Inventario de Depresión de Beck (IDB-II), los de ansiedad con la correspondiente subescala del Hopkins Symptom Check List 90 (SCL-90) y el apoyo social con la escala de Apoyo Social Apgar (SSA). Una selección de 12 reactivos sobre estresores potenciales y dificultades persistentes se usó para medir sucesos vitales y la Escala de Ajuste Diádico (A-DAS) para evaluar la satisfacción con la relación de pareja. Resultados Las tasas de retención definidas de tres maneras fueron: 1. La retención total (participantes aleatorizadas que concluyeron con todo el procedimiento hasta la entrevista a los 4-6 meses posparto) fue de 41.7% (31.2% intervención y 61.4% control). 2. La retención desde la aleatorización hasta (a) completar la entrevista inicial y asistir a > 1 sesión de intervención fue de 42.4% y (b) completar la evaluación inicial (control) fue de 82.2% (c). 3. La retención hasta el seguimiento: (a) proporción que inició y completó la intervención, esto es, que asistió a > 4 sesiones, así como a la entrevista a los 4-6 meses posparto fue de 73.5% y (b) participantes del grupo control que fueron entrevistadas en este periodo fue de 66.6%. Para quienes asistieron a por lo menos una sesión, la tasa de asistencia a la intervención fue de 83%. Las variables que predijeron la retención totalfueron: ser soltera, tener mayor nivel de escolaridad y la mala relación de pareja. En el grupo de intervención, las variables que predijeron (a) la retención desde la aleatorización hasta asistir a > 1 sesión de intervención fueron la presencia de ansiedad y de sucesos estresantes, y (b) la retención hasta el seguimiento aumentó en mujeres que estaban o habían estado empleadas los últimos seis meses. Conclusiones Los resultados son consistentes con los de trabajos anteriores respecto a la dificultad para retener mujeres embarazadas y en el puerperio en ensayos a lo largo del tiempo. En el presente estudio la tasa de retención fue aún más baja de lo que han encontrado otros autores, sobre todo debido a la enorme pérdida de participantes que firmaron el consentimiento informado y fueron aleatorizadas y no asistieron a ninguna sesión de la intervención. Al mismo tiempo, es interesante notar que la tasa de asistencia a la intervención, una vez que las participantes se presentaron a una primera sesión, fue muy alta. Esto habla de la alta aceptación que ésta tuvo entre las participantes. En cuanto a los factores que predijeron la retención, las mujeres con alto riesgo de depresión (sin pareja, con una relación mala con la pareja, con más sucesos estresantes y síntomas de ansiedad) fueron las más comprometidas en participar en el estudio. Por lo tanto, una manera de mejorar la tasa de retención es a través de dirigirla a mujeres que presenten estos factores de riesgo. Por otro lado, fue difícil retener a aquellas con bajo nivel de escolaridad y a las amas de casa, que también son una población vulnerable. Saber cómo mejorar la retención de este grupo sigue siendo un reto para estudios posteriores de prevención de la depresión posparto. Podemos concluir que las tasas y los factores que predicen la retención varían dependiendo de la manera en que se definan, lo que sugiere que las estrategias para optimizar la retención deben adecuarse a cada una de estas definiciones. <![CDATA[<b>Profiles and psychological indicators related to dyspareunia and vaginismus</b>: <b>Qualitative study. Part two</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500008&lng=pt&nrm=iso&tlng=pt One target of psychology of health is the quest for specificity when detecting factors related to psychological disorders, among which there are female sexual dysfunctions showing associated pain: dyspareunia and vaginismus (not caused by medical disease). Dyspareunia is the presence of genital pain during sexual intercourse and is related to psychological or relational factors. Vaginismus is characterized by spasms in the muscles of the vaginal entrance, making it difficult or impossible to perform coitus; the woman can be sexually aroused, responsive and enjoying sexual games, she can even reach her orgasm, as long as there is no penetration. Of all the causes mentioned, the following are recognized: incapacity to let go to the erotic experience, fear to failure, cultural influence predisposing sexual conflict, anxiety and shame, as well as couple problems. However, specificity is lacking in the factors related to each one of these sexual dysfunctions in order to provide elements generating intervention strategies. Objective The objective is to detect new indicators with the purpose of having a better understanding of why an individual exercises sexuality in such a way that it makes her have a proper sexual response and why, in other situations, the sexual response shows alterations leading to dyspareunia or vaginismus. Four are the specific objectives: 1. Identification of current indicators that have an influence in sexual dysfunctions of the participants. 2. Identification of indicators that have had an influence in the unsatisfactory development of sexuality of the participants. 3. Identification of elements of perception of the participants in the couple life of their parents that may have had an impact on their sexuality. 4. Identification of indicators that, within the sexual management provided by the family, had an impact in the sexual life of the participants. Material and methods The qualitative-interpretative method was used, in the form of an exploratory case-study. The institution where the study took place was the Department of Psychology of the National Institute of Perinatology (INPerlER). The sample was constituted by three participants, all of them patients from the institution; they had to comply with certain inclusion criteria of the study. Any physical problem that could have caused the sexual dysfunction was discarded. The first participant did not show any sexual dysfunction (NSD), the second one showed dyspareunia (D) and the third one showed vaginismus (V). We used a semi-structured, focalized, in-depth interview. Interviews took place after having signed a letter of informed consent, accordingly to the ethical institutional requirements, and we also got an approval of recording the interview. We used the analysis of content with an empiric, exploratory orientation. Categories were organized accordingly with the specific objectives. Results The three participants were: NSD: 32 years old, five years of marriage. No sexual dysfunction. V: 36 years old, six years of marriage. Diagnosis: vaginismus. D: 33 years old, one year in free union. Diagnosis: dyspareunia. Data systematization was performed dividing the units of analysis by every participant and the parts of the most significative stories of every specific objective within its respective categories. In the analysis of categories we detected two conditions: internal and relational, as well as two types of indicators: risk indicators and protective indicators. What marked the difference was the dominium of the protective indicators overthe risk indicators in the NSD participant. Among the more important risk indicators, we found feelings of disadvantage, uselessness and devaluating feelings, linked to a tendency to submissive behavior, as a consequence of remote causes such as having faced a double moral in the family: on the one hand erotized family bonds during infancy and, on the other hand, prohibitions and stiffness towards any sexual curiosity or manifestation, apart from a poor socialization. The conflict between desire and sexual prohibition generates confusion in the identification of sensations, setting a painful, fearful association to sexuality, even moreso if this landscape is complicated with other elements such as violence and carelessness. Other elements found as a consequence of the aforementioned include self-inflicted violence, annulment of desire, lack of self-care and interacting problems with the opposite sex in everyday life. All of this leads to an incapacity of exerting a satisfactory sexual life, drifting towards secondary fears when feeling disadvantageous while interacting with the couple; this, in great extent, determines the conflicts, which maybe either a cause or a consequence of the sexual problem. Confusion also arises when trying to identify whether problems are internal or external, thence conductual responses tend to complicate the relationship. In both sexual dysfunctions we find a specific type of frustration, since desire, excitement and orgasm are present, but coitus cannot be performed in a satisfactory way. The following are the more important protective indicators: conductual assertive responses, clarity in the affections, situation of the problems, search for sexual information, openness to family communication and with the couple, a couple's differential place, plus the search of satisfaction of sexuality and self care. Among the indicators shared we found: limited or null sexual education, poor communication in the family nucleus, and gender stereotypes highly polarized between parents, among others. Conclusions We corroborate in this study that it is the combination of specific elements which contributes to the presence of these two sexual dysfunctions, since the psychological world has many intertwined streams, intervention models cannot be centered only in sexual techniques, but they should also consider the indicators related to such alterations. Finally, it must be pointed out that the results of this phase are the product of an exploratory study, opening the gates to new lines of research.<hr/>Una de las metas de la psicología de la salud es la búsqueda de especificidad en la detección de factores relacionados con los trastornos psicológicos, entre los que se encuentran las disfunciones sexuales femeninas por dolor: la dispareunia y el vaginismo (no debidas a enfermedad médica). La dispareunia es la presencia de dolor genital en la relación sexual. El vaginismo se caracteriza por espasmos de la musculatura de la entrada vaginal que dificultan o hacen imposible la realización del coito. Entre las causas se mencionan la incapacidad de abandonarse a la experiencia erótica, temor al fracaso, etc. Sin embargo, hace falta especificar los factores relacionados con éstas disfunciones sexuales para obtener elementos generadores de estrategias de intervención. Objetivo de la segunda fase Detectar indicadores para tener una mayor comprensión de por qué una mujer tiene un ejercicio de la sexualidad que la lleva a tener una respuesta sexual adecuada y por qué en otra la respuesta sexual presenta alteraciones que dan como resultado la presencia de dispareunia o vaginismo. Los objetivos específicos son cuatro: 1. Identificar indicadores actuales que influyen en la presencia de disfunciones sexuales de las participantes. 2. Identificar indicadores que hayan influido en el desarrollo insatisfactorio de la sexualidad de las participantes. 3. Identificar elementos de la percepción que tienen las participantes de la vida en pareja de sus padres, que pudieron impactar en su sexualidad. 4. Identificar procesos que dentro de la dinámica familiar impactaron la vida sexual de las participantes. Material y método Se utilizó el método cualitativo-interpretativo, estudio de casos y exploratorio. El escenario fue el Departamento de Psicología del Instituto Nacional de Perinatología (INPerlER), se entrevistó a tres participantes pacientes de éste. La primera sin disfunción sexual (SDS), la segunda con dispareunia (D) y, la tercera con vaginismo (V). Se utilizó la entrevista en profundidad semi-estructurada y se trabajó con análisis de contenido. Las categorías se organizaron de acuerdo a los objetivos específicos. Resultados La sistematización de los datos se realizó dividiendo las unidades de análisis por cada participante de cada objetivo específico. Se detectaron dos condiciones: las internas y las relaciónales, así como dos tipos de indicadores: los de riesgo y los protectores. Lo que marcó la diferencia fue el predominio de los indicadores protectores sobre los de riesgo en la participante SDS. Entre los indicadores de riesgo se encuentran sentimientos de desventaja, de inutilidad y devaluatorios, ligados a una tendencia a la sumisión; ello como consecuencia de causas remotas, como haber enfrentado una doble moral familiar. El conflicto entre deseo y prohibición sexual genera confusión, estableciéndose una asociación doloroso y llena de temores hacia la sexualidad. Otro elemento encontrado, consecuencia de lo anterior, es la violencia al propio cuerpo, la anulación del deseo, falta de autocuidado y problemas en la interacción con el sexo opuesto en su vida actual. De los indicadores protectores están las respuestas conductuales asertivas, la claridad de sus afectos, ubicación de los problemas, búsqueda de información sexual, apertura en la comunicación familiar y con la pareja, búsqueda de satisfacción de su sexualidad y autocuidado. Entre los indicadores que comparten se encuentra una limitada educación sexual, pobre comunicación en el núcleo familiar y estereotipos de género muy polarizados de los padres. Conclusiones Es la combinación de elementos específicos que se presentan de manera cotidiana los que implican un mayor riesgo para desarrollar estas disfunciones sexuales, los modelos de intervención no pueden únicamente centrarse en las técnicas sexuales y deben contemplar los indicadores relacionados con estas alteraciones. Cabe señalar que los resultados son producto de un estudio exploratorio que abre las puertas para nuevas líneas de investigación y de los cuales no se pueden hacer generalizaciones. <![CDATA[<b>Brain, drugs, its neurobiological mechanisms</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500009&lng=pt&nrm=iso&tlng=pt The pleasant sensation experienced when, for example eating or having sex is regulated by the motivation-rewarding system. This rewarding sensation makes the subject to repeat the behavior in order to obtain the reinforcer once more. This system can be corrupted by drugs of abuse by triggering an «intense feeling of pleasure» and inducing plastic changes. In normal conditions, a natural reinforcer is a stimulus generating a benefit to the organism. For example, food will provide energy and structure among many other benefits. Sex, in turn, accomplishes the function of giving new beings to the species and to create boundaries between subjects to generate groups and culture. Due to these facts, it is crucial to reinforce this kind of behaviors. They are crucial for the subject's life. In contrast, drugs do not produce any benefit to the subject or group. Although in ancient times human beings used drugs as a means to develop and practice their mysticism, such practice is no longer associated with the use of drugs. With the exception of present time aboriginal communities, none of the regular users in our countries consume drugs with ritual-mystical purposes. Hence, we have to accept that drugs are of no use for human beings. They do not help us as species to have more adapted, intelligent or developed subjects in our communities. However, their ability to stimulate the rewarding system makes them popular and dangerous to the individual's health and life. The motivation-rewarding system is regulated by numerous neurotransmitters, among them dopamine, that is released in the nucleus accumbens (NAc) and synthesized by the neurons located in the ventral tegmetal area (VTA). There are other substances that modulate the activity of the dopaminergic neurons in the VTA, such as serotonin, acetylcholine, gamma-aminobutyric acid (GABA) and glutamate. The activation of the VTA and its consequent activation of the NAc enhance the release of neuromodulators such as endorphins and endocannabinoids, thus generating the subjective sensation of pleasure. All these interactions trigger the activity of memory systems generating a memory trace encoding the characteristics of the substance or behavior causing pleasure. This occurs in the context that the brain accepts these substances or behaviors as beneficial to the organism. The punishment system is also a very important system working in tight communication with the pleasure system. Fear is one of the most critical adapting behaviors for any subject in the animal kingdom. Fear helps us to avoid dangerous stimulus and behaviors. There is also pleasure involved in escaping this kind of situations. It seems like there is an interaction between the motivation-rewarding and the punishment systems. As a result, there is a balance at times in favor of pleasure, at times in favor of punishment depending on the quality of the stimulus. This balance gives the valence to the emotion triggered by the stimulus. A stimulus with a positive valence will increase the probability of exhibiting the behavior displayed to obtain it, while a stimulus with a negative valence will increase the probability of exhibiting the behavior displayed to avoid it. In this context, the so-called non-natural reinforcers such as drugs of abuse act directly on the pleasure system. For example, nicotine acts on the nicotinic receptor of ACh, alcohol, on the receptor of GABAa and glutamate (NMDA), marihuana on the endocannabinoid receptor (CB1 R), located in the motivation-rewarding system triggering an «intense sensation of pleasure». However, two main shortcomings make drugs of abuse dangerous: first, their effect is short and, second, they do not convey any beneficial effect to the organism whatsoever. Brain mechanisms not very well defined detect this lack of benefit; hence, the motivation-rewarding system reduces its response by means of at least two plastic changes, reducing the availability of receptors (epigenetic changes induced by the drug) and by increasing the activity of the punishment system to maintain the balance. As a result, the subject does not experience the same pleasure with the same dose of the drug. In the clinic we call this phenomenon tolerance. If the individual insists in pursuing the same intensity of pleasure, he/she has to consume more of the drug, forcing the brain to strengthen its plastic changes. In this context, we can say that these systems are defending themselves against the action of the drug. Then, why do subjects insist in pursuing the effect of drugs? Very likely because the substrate of the subject's disorder resides anywhere in the brain but in the pleasure system. If so, this indicates that drug addiction is a disorder caused by another disease, very likely a psychiatric one. Several factors contribute to generate drug addiction, i. e. social, psychological and genetic. Genes contribute in different ways to generate the subject's vulnerability to suffer an addiction. A gene mutation (alteration in genetic information) or a given polymorphism (the existence of multiple alleles of a gene in a population) can produce a dysfunctional protein or alter its normal levels. Such changes may make some individuals vulnerable to the initial use of drugs of abuse. However, those genes facilitating adjustments in the motivation-rewarding system that occur after the repeated consumption of drugs of abuse seem to be functioning normally, as we can infer from the development of tolerance. The heritability of these genes, making subjects vulnerable to addiction, has been studied in many ways, including studies of families, adoptees, and twins (monozygotic and dizygotic). From these studies it has been possible to calculate the heritability index, a measure which indicates how much variance of a trait in a specific sample is associated to genetic factors and how much to the environment. The heritability index has a range from 1, meaning the maximum genetic influence, to 0, meaning the maximum environment influence. At present, a significant number of genes have been involved in facilitating addiction to drugs, and also very important, to the response to treatment for rehabilitation. The expression of the genes is regulated by a series of processes called epigenesis. Epigenetic changes can be a result of the interaction between genes and environment. This interaction results in chemical processes that modify chromatin structure. For example, cytosine nucleotide methylation causes chromatin condensation, which interferes with gene transcription; hence, the protein encoded by this gene will be reduced, and the function in which it participates will be altered. As an example, when the methylation of the gene encoding for the glucocorticoid receptor occurs in rats, it reduces the bioavailability of this receptor and increases the release of corticosterone when rats are stressed. At the behavioral level, rats seem to be more stressed most of the time as compared with rats without methylation of this gene. Almost every stimulus in the environment is a potential promoter of epigenesis. Epigenesis is important to occur, since it is an adaptive response of the organism to the environment. It seems like the switches of the genes are turned on or off according to environment circumstances. These genetic changes will be ultimately expressed as plastic changes pursuing the right adaptation of the subject to the environment. Parental care seems to be one crucial contributor to these epigenetic modifications. For example, when a mother-rat provides poor care (feeding, grooming, and physical contact) to its litter during the neonate period, facilitates the methylation of genes, as it has been proved for the glucocorticoid receptor. These changes generate subjects with poor stress management and less capability for learning. Likewise, it makes them susceptible to drug addiction. These results highlight the importance of parental care as provider of a healthy environment, which is modeling the expression of their genes, hence their behavior.<hr/>La definición de adicción propuesta por la Organización Mundial de la Salud, dicha de manera sucinta, indica que es una enfermedad cerebral que provoca una búsqueda compulsiva de la droga y su uso, a pesar de las consecuencias adversas que ésta provoque. La fisiopatología de la enfermedad sugiere una interacción entre mecanismos cerebrales, cambios genéticos y medio ambiente. El objetivo de este artículo es discutir la evidencia que existe sobre los sistemas cerebrales que son afectados por las drogas, qué genes participan y cómo el medio ambiente tiene una participación crucial para generar esta enfermedad. Discutiremos tres secciones: el cerebro, las drogas y los genes. La primera trata sobre cómo el cerebro responde ante estímulos reforzantes y cómo estos sistemas cerebrales promueven que el individuo repita la conducta que lo llevó a adquirir el reforzador originalmente, para obtenerlo de nuevo. A este sistema se le denomina sistema de motivación-recompensa. Este sistema responde muy activamente ante reforzadores naturales (estímulos que buscan preservar la vida del individuo), pero también a reforzadores no naturales. En este grupo de estímulos están las drogas de abuso. El sistema de motivación-recompensa está modulado por diversas estructuras subcorticales y corticales que incluyen un sistema de castigo. Estos sistemas util izan una gran diversidad de neurotransmisores y neuromoduladores que inducirán una sensación de placer ante la presencia del estímulo reforzante. Todas las drogas de abuso provocan un efecto sobre los receptores y sobre los transportadores de los neurotransmisores, al igual que sobre las enzimas que participan en la síntesis y degradación de estos mediadores químicos. El uso repetido de la droga modifica así estructural y funcionalmente al cerebro. Estos cambios plásticos desarrollados en el sistema de la motivación-recompensa y también en el de castigo, provocan un nuevo balance entre ellos que lleva al individuo a un estado de alostasis, en el cual la droga se convierte en una necesidad. En otro artículo haremos una reseña sobre drogas lícitas e ilícitas; sus efectos, sus sitios de acción y las consecuencias adversas de su uso. La última sección versará sobre la genética: definimos los conceptos de gen y alelo, de mutación y polimorfismo, heredabilidad y epigenética, a fin de entender qué hace a un individuo vulnerable a la adicción de una droga de abuso. Si bien para la adicción existe una contribución ambiental, la contribución genética es importante. Esta contribución no es igual para las diferentes drogas. La cocaína y los opiáceos, no solamente son las drogas más adictivas, sino también las que mayor contribución genética tienen en comparación con otras (v. gr. nicotina, alcohol o marihuana). Los polimorfismos en diversos genes hacen vulnerable a un cerebro para convertirse en adicto a alguna droga o, por el contrario, dificultan la eficiencia de los tratamientos en contra de la adicción. Entre los polimorfismos que se han descrito son de interés los genes que codifican para las enzimas hepáticas citocromo P450, ya que estos polimorfismos modifican la vulnerabilidad para la adicción al tabaco, al alcohol y a la heroína. Es menester considerar la influencia genética en la adicción puesto que las variaciones a este nivel harán responder diferencialmente al tratamiento a personas con el mismo tipo de adicción. Por ello, hay que enfatizar el uso individualizado de la terapia. Por último, planteamos que quienes buscarán con mayor probabilidad el uso de una droga son quienes presentan una enfermedad psiquiátrica de fondo, así que la adicción representa sólo una parte de una enfermedad dual o comorbilidad. En este contexto, la hipótesis de la automedicación sugiere que los pacientes buscan la droga con el fin de controlar su patología inicial. Esta revisión busca integrar la interacción entre el cerebro, las drogas y los genes, pero no pretende ser exhaustiva. Nuestro interés es dar un panorama al lector sobre cómo estos tres mundos convergen, para entender cómo ocurre esta enfermedad y tratarla diferencialmente entre los individuos. <![CDATA[<b>The hakik</b>: <b>remedy or poison?</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500010&lng=pt&nrm=iso&tlng=pt The pleasant sensation experienced when, for example eating or having sex is regulated by the motivation-rewarding system. This rewarding sensation makes the subject to repeat the behavior in order to obtain the reinforcer once more. This system can be corrupted by drugs of abuse by triggering an «intense feeling of pleasure» and inducing plastic changes. In normal conditions, a natural reinforcer is a stimulus generating a benefit to the organism. For example, food will provide energy and structure among many other benefits. Sex, in turn, accomplishes the function of giving new beings to the species and to create boundaries between subjects to generate groups and culture. Due to these facts, it is crucial to reinforce this kind of behaviors. They are crucial for the subject's life. In contrast, drugs do not produce any benefit to the subject or group. Although in ancient times human beings used drugs as a means to develop and practice their mysticism, such practice is no longer associated with the use of drugs. With the exception of present time aboriginal communities, none of the regular users in our countries consume drugs with ritual-mystical purposes. Hence, we have to accept that drugs are of no use for human beings. They do not help us as species to have more adapted, intelligent or developed subjects in our communities. However, their ability to stimulate the rewarding system makes them popular and dangerous to the individual's health and life. The motivation-rewarding system is regulated by numerous neurotransmitters, among them dopamine, that is released in the nucleus accumbens (NAc) and synthesized by the neurons located in the ventral tegmetal area (VTA). There are other substances that modulate the activity of the dopaminergic neurons in the VTA, such as serotonin, acetylcholine, gamma-aminobutyric acid (GABA) and glutamate. The activation of the VTA and its consequent activation of the NAc enhance the release of neuromodulators such as endorphins and endocannabinoids, thus generating the subjective sensation of pleasure. All these interactions trigger the activity of memory systems generating a memory trace encoding the characteristics of the substance or behavior causing pleasure. This occurs in the context that the brain accepts these substances or behaviors as beneficial to the organism. The punishment system is also a very important system working in tight communication with the pleasure system. Fear is one of the most critical adapting behaviors for any subject in the animal kingdom. Fear helps us to avoid dangerous stimulus and behaviors. There is also pleasure involved in escaping this kind of situations. It seems like there is an interaction between the motivation-rewarding and the punishment systems. As a result, there is a balance at times in favor of pleasure, at times in favor of punishment depending on the quality of the stimulus. This balance gives the valence to the emotion triggered by the stimulus. A stimulus with a positive valence will increase the probability of exhibiting the behavior displayed to obtain it, while a stimulus with a negative valence will increase the probability of exhibiting the behavior displayed to avoid it. In this context, the so-called non-natural reinforcers such as drugs of abuse act directly on the pleasure system. For example, nicotine acts on the nicotinic receptor of ACh, alcohol, on the receptor of GABAa and glutamate (NMDA), marihuana on the endocannabinoid receptor (CB1 R), located in the motivation-rewarding system triggering an «intense sensation of pleasure». However, two main shortcomings make drugs of abuse dangerous: first, their effect is short and, second, they do not convey any beneficial effect to the organism whatsoever. Brain mechanisms not very well defined detect this lack of benefit; hence, the motivation-rewarding system reduces its response by means of at least two plastic changes, reducing the availability of receptors (epigenetic changes induced by the drug) and by increasing the activity of the punishment system to maintain the balance. As a result, the subject does not experience the same pleasure with the same dose of the drug. In the clinic we call this phenomenon tolerance. If the individual insists in pursuing the same intensity of pleasure, he/she has to consume more of the drug, forcing the brain to strengthen its plastic changes. In this context, we can say that these systems are defending themselves against the action of the drug. Then, why do subjects insist in pursuing the effect of drugs? Very likely because the substrate of the subject's disorder resides anywhere in the brain but in the pleasure system. If so, this indicates that drug addiction is a disorder caused by another disease, very likely a psychiatric one. Several factors contribute to generate drug addiction, i. e. social, psychological and genetic. Genes contribute in different ways to generate the subject's vulnerability to suffer an addiction. A gene mutation (alteration in genetic information) or a given polymorphism (the existence of multiple alleles of a gene in a population) can produce a dysfunctional protein or alter its normal levels. Such changes may make some individuals vulnerable to the initial use of drugs of abuse. However, those genes facilitating adjustments in the motivation-rewarding system that occur after the repeated consumption of drugs of abuse seem to be functioning normally, as we can infer from the development of tolerance. The heritability of these genes, making subjects vulnerable to addiction, has been studied in many ways, including studies of families, adoptees, and twins (monozygotic and dizygotic). From these studies it has been possible to calculate the heritability index, a measure which indicates how much variance of a trait in a specific sample is associated to genetic factors and how much to the environment. The heritability index has a range from 1, meaning the maximum genetic influence, to 0, meaning the maximum environment influence. At present, a significant number of genes have been involved in facilitating addiction to drugs, and also very important, to the response to treatment for rehabilitation. The expression of the genes is regulated by a series of processes called epigenesis. Epigenetic changes can be a result of the interaction between genes and environment. This interaction results in chemical processes that modify chromatin structure. For example, cytosine nucleotide methylation causes chromatin condensation, which interferes with gene transcription; hence, the protein encoded by this gene will be reduced, and the function in which it participates will be altered. As an example, when the methylation of the gene encoding for the glucocorticoid receptor occurs in rats, it reduces the bioavailability of this receptor and increases the release of corticosterone when rats are stressed. At the behavioral level, rats seem to be more stressed most of the time as compared with rats without methylation of this gene. Almost every stimulus in the environment is a potential promoter of epigenesis. Epigenesis is important to occur, since it is an adaptive response of the organism to the environment. It seems like the switches of the genes are turned on or off according to environment circumstances. These genetic changes will be ultimately expressed as plastic changes pursuing the right adaptation of the subject to the environment. Parental care seems to be one crucial contributor to these epigenetic modifications. For example, when a mother-rat provides poor care (feeding, grooming, and physical contact) to its litter during the neonate period, facilitates the methylation of genes, as it has been proved for the glucocorticoid receptor. These changes generate subjects with poor stress management and less capability for learning. Likewise, it makes them susceptible to drug addiction. These results highlight the importance of parental care as provider of a healthy environment, which is modeling the expression of their genes, hence their behavior.<hr/>La definición de adicción propuesta por la Organización Mundial de la Salud, dicha de manera sucinta, indica que es una enfermedad cerebral que provoca una búsqueda compulsiva de la droga y su uso, a pesar de las consecuencias adversas que ésta provoque. La fisiopatología de la enfermedad sugiere una interacción entre mecanismos cerebrales, cambios genéticos y medio ambiente. El objetivo de este artículo es discutir la evidencia que existe sobre los sistemas cerebrales que son afectados por las drogas, qué genes participan y cómo el medio ambiente tiene una participación crucial para generar esta enfermedad. Discutiremos tres secciones: el cerebro, las drogas y los genes. La primera trata sobre cómo el cerebro responde ante estímulos reforzantes y cómo estos sistemas cerebrales promueven que el individuo repita la conducta que lo llevó a adquirir el reforzador originalmente, para obtenerlo de nuevo. A este sistema se le denomina sistema de motivación-recompensa. Este sistema responde muy activamente ante reforzadores naturales (estímulos que buscan preservar la vida del individuo), pero también a reforzadores no naturales. En este grupo de estímulos están las drogas de abuso. El sistema de motivación-recompensa está modulado por diversas estructuras subcorticales y corticales que incluyen un sistema de castigo. Estos sistemas util izan una gran diversidad de neurotransmisores y neuromoduladores que inducirán una sensación de placer ante la presencia del estímulo reforzante. Todas las drogas de abuso provocan un efecto sobre los receptores y sobre los transportadores de los neurotransmisores, al igual que sobre las enzimas que participan en la síntesis y degradación de estos mediadores químicos. El uso repetido de la droga modifica así estructural y funcionalmente al cerebro. Estos cambios plásticos desarrollados en el sistema de la motivación-recompensa y también en el de castigo, provocan un nuevo balance entre ellos que lleva al individuo a un estado de alostasis, en el cual la droga se convierte en una necesidad. En otro artículo haremos una reseña sobre drogas lícitas e ilícitas; sus efectos, sus sitios de acción y las consecuencias adversas de su uso. La última sección versará sobre la genética: definimos los conceptos de gen y alelo, de mutación y polimorfismo, heredabilidad y epigenética, a fin de entender qué hace a un individuo vulnerable a la adicción de una droga de abuso. Si bien para la adicción existe una contribución ambiental, la contribución genética es importante. Esta contribución no es igual para las diferentes drogas. La cocaína y los opiáceos, no solamente son las drogas más adictivas, sino también las que mayor contribución genética tienen en comparación con otras (v. gr. nicotina, alcohol o marihuana). Los polimorfismos en diversos genes hacen vulnerable a un cerebro para convertirse en adicto a alguna droga o, por el contrario, dificultan la eficiencia de los tratamientos en contra de la adicción. Entre los polimorfismos que se han descrito son de interés los genes que codifican para las enzimas hepáticas citocromo P450, ya que estos polimorfismos modifican la vulnerabilidad para la adicción al tabaco, al alcohol y a la heroína. Es menester considerar la influencia genética en la adicción puesto que las variaciones a este nivel harán responder diferencialmente al tratamiento a personas con el mismo tipo de adicción. Por ello, hay que enfatizar el uso individualizado de la terapia. Por último, planteamos que quienes buscarán con mayor probabilidad el uso de una droga son quienes presentan una enfermedad psiquiátrica de fondo, así que la adicción representa sólo una parte de una enfermedad dual o comorbilidad. En este contexto, la hipótesis de la automedicación sugiere que los pacientes buscan la droga con el fin de controlar su patología inicial. Esta revisión busca integrar la interacción entre el cerebro, las drogas y los genes, pero no pretende ser exhaustiva. Nuestro interés es dar un panorama al lector sobre cómo estos tres mundos convergen, para entender cómo ocurre esta enfermedad y tratarla diferencialmente entre los individuos. <![CDATA[<b>Agresión y violencia</b>: <b>Cerebro, comportamiento y bioética</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500011&lng=pt&nrm=iso&tlng=pt The pleasant sensation experienced when, for example eating or having sex is regulated by the motivation-rewarding system. This rewarding sensation makes the subject to repeat the behavior in order to obtain the reinforcer once more. This system can be corrupted by drugs of abuse by triggering an «intense feeling of pleasure» and inducing plastic changes. In normal conditions, a natural reinforcer is a stimulus generating a benefit to the organism. For example, food will provide energy and structure among many other benefits. Sex, in turn, accomplishes the function of giving new beings to the species and to create boundaries between subjects to generate groups and culture. Due to these facts, it is crucial to reinforce this kind of behaviors. They are crucial for the subject's life. In contrast, drugs do not produce any benefit to the subject or group. Although in ancient times human beings used drugs as a means to develop and practice their mysticism, such practice is no longer associated with the use of drugs. With the exception of present time aboriginal communities, none of the regular users in our countries consume drugs with ritual-mystical purposes. Hence, we have to accept that drugs are of no use for human beings. They do not help us as species to have more adapted, intelligent or developed subjects in our communities. However, their ability to stimulate the rewarding system makes them popular and dangerous to the individual's health and life. The motivation-rewarding system is regulated by numerous neurotransmitters, among them dopamine, that is released in the nucleus accumbens (NAc) and synthesized by the neurons located in the ventral tegmetal area (VTA). There are other substances that modulate the activity of the dopaminergic neurons in the VTA, such as serotonin, acetylcholine, gamma-aminobutyric acid (GABA) and glutamate. The activation of the VTA and its consequent activation of the NAc enhance the release of neuromodulators such as endorphins and endocannabinoids, thus generating the subjective sensation of pleasure. All these interactions trigger the activity of memory systems generating a memory trace encoding the characteristics of the substance or behavior causing pleasure. This occurs in the context that the brain accepts these substances or behaviors as beneficial to the organism. The punishment system is also a very important system working in tight communication with the pleasure system. Fear is one of the most critical adapting behaviors for any subject in the animal kingdom. Fear helps us to avoid dangerous stimulus and behaviors. There is also pleasure involved in escaping this kind of situations. It seems like there is an interaction between the motivation-rewarding and the punishment systems. As a result, there is a balance at times in favor of pleasure, at times in favor of punishment depending on the quality of the stimulus. This balance gives the valence to the emotion triggered by the stimulus. A stimulus with a positive valence will increase the probability of exhibiting the behavior displayed to obtain it, while a stimulus with a negative valence will increase the probability of exhibiting the behavior displayed to avoid it. In this context, the so-called non-natural reinforcers such as drugs of abuse act directly on the pleasure system. For example, nicotine acts on the nicotinic receptor of ACh, alcohol, on the receptor of GABAa and glutamate (NMDA), marihuana on the endocannabinoid receptor (CB1 R), located in the motivation-rewarding system triggering an «intense sensation of pleasure». However, two main shortcomings make drugs of abuse dangerous: first, their effect is short and, second, they do not convey any beneficial effect to the organism whatsoever. Brain mechanisms not very well defined detect this lack of benefit; hence, the motivation-rewarding system reduces its response by means of at least two plastic changes, reducing the availability of receptors (epigenetic changes induced by the drug) and by increasing the activity of the punishment system to maintain the balance. As a result, the subject does not experience the same pleasure with the same dose of the drug. In the clinic we call this phenomenon tolerance. If the individual insists in pursuing the same intensity of pleasure, he/she has to consume more of the drug, forcing the brain to strengthen its plastic changes. In this context, we can say that these systems are defending themselves against the action of the drug. Then, why do subjects insist in pursuing the effect of drugs? Very likely because the substrate of the subject's disorder resides anywhere in the brain but in the pleasure system. If so, this indicates that drug addiction is a disorder caused by another disease, very likely a psychiatric one. Several factors contribute to generate drug addiction, i. e. social, psychological and genetic. Genes contribute in different ways to generate the subject's vulnerability to suffer an addiction. A gene mutation (alteration in genetic information) or a given polymorphism (the existence of multiple alleles of a gene in a population) can produce a dysfunctional protein or alter its normal levels. Such changes may make some individuals vulnerable to the initial use of drugs of abuse. However, those genes facilitating adjustments in the motivation-rewarding system that occur after the repeated consumption of drugs of abuse seem to be functioning normally, as we can infer from the development of tolerance. The heritability of these genes, making subjects vulnerable to addiction, has been studied in many ways, including studies of families, adoptees, and twins (monozygotic and dizygotic). From these studies it has been possible to calculate the heritability index, a measure which indicates how much variance of a trait in a specific sample is associated to genetic factors and how much to the environment. The heritability index has a range from 1, meaning the maximum genetic influence, to 0, meaning the maximum environment influence. At present, a significant number of genes have been involved in facilitating addiction to drugs, and also very important, to the response to treatment for rehabilitation. The expression of the genes is regulated by a series of processes called epigenesis. Epigenetic changes can be a result of the interaction between genes and environment. This interaction results in chemical processes that modify chromatin structure. For example, cytosine nucleotide methylation causes chromatin condensation, which interferes with gene transcription; hence, the protein encoded by this gene will be reduced, and the function in which it participates will be altered. As an example, when the methylation of the gene encoding for the glucocorticoid receptor occurs in rats, it reduces the bioavailability of this receptor and increases the release of corticosterone when rats are stressed. At the behavioral level, rats seem to be more stressed most of the time as compared with rats without methylation of this gene. Almost every stimulus in the environment is a potential promoter of epigenesis. Epigenesis is important to occur, since it is an adaptive response of the organism to the environment. It seems like the switches of the genes are turned on or off according to environment circumstances. These genetic changes will be ultimately expressed as plastic changes pursuing the right adaptation of the subject to the environment. Parental care seems to be one crucial contributor to these epigenetic modifications. For example, when a mother-rat provides poor care (feeding, grooming, and physical contact) to its litter during the neonate period, facilitates the methylation of genes, as it has been proved for the glucocorticoid receptor. These changes generate subjects with poor stress management and less capability for learning. Likewise, it makes them susceptible to drug addiction. These results highlight the importance of parental care as provider of a healthy environment, which is modeling the expression of their genes, hence their behavior.<hr/>La definición de adicción propuesta por la Organización Mundial de la Salud, dicha de manera sucinta, indica que es una enfermedad cerebral que provoca una búsqueda compulsiva de la droga y su uso, a pesar de las consecuencias adversas que ésta provoque. La fisiopatología de la enfermedad sugiere una interacción entre mecanismos cerebrales, cambios genéticos y medio ambiente. El objetivo de este artículo es discutir la evidencia que existe sobre los sistemas cerebrales que son afectados por las drogas, qué genes participan y cómo el medio ambiente tiene una participación crucial para generar esta enfermedad. Discutiremos tres secciones: el cerebro, las drogas y los genes. La primera trata sobre cómo el cerebro responde ante estímulos reforzantes y cómo estos sistemas cerebrales promueven que el individuo repita la conducta que lo llevó a adquirir el reforzador originalmente, para obtenerlo de nuevo. A este sistema se le denomina sistema de motivación-recompensa. Este sistema responde muy activamente ante reforzadores naturales (estímulos que buscan preservar la vida del individuo), pero también a reforzadores no naturales. En este grupo de estímulos están las drogas de abuso. El sistema de motivación-recompensa está modulado por diversas estructuras subcorticales y corticales que incluyen un sistema de castigo. Estos sistemas util izan una gran diversidad de neurotransmisores y neuromoduladores que inducirán una sensación de placer ante la presencia del estímulo reforzante. Todas las drogas de abuso provocan un efecto sobre los receptores y sobre los transportadores de los neurotransmisores, al igual que sobre las enzimas que participan en la síntesis y degradación de estos mediadores químicos. El uso repetido de la droga modifica así estructural y funcionalmente al cerebro. Estos cambios plásticos desarrollados en el sistema de la motivación-recompensa y también en el de castigo, provocan un nuevo balance entre ellos que lleva al individuo a un estado de alostasis, en el cual la droga se convierte en una necesidad. En otro artículo haremos una reseña sobre drogas lícitas e ilícitas; sus efectos, sus sitios de acción y las consecuencias adversas de su uso. La última sección versará sobre la genética: definimos los conceptos de gen y alelo, de mutación y polimorfismo, heredabilidad y epigenética, a fin de entender qué hace a un individuo vulnerable a la adicción de una droga de abuso. Si bien para la adicción existe una contribución ambiental, la contribución genética es importante. Esta contribución no es igual para las diferentes drogas. La cocaína y los opiáceos, no solamente son las drogas más adictivas, sino también las que mayor contribución genética tienen en comparación con otras (v. gr. nicotina, alcohol o marihuana). Los polimorfismos en diversos genes hacen vulnerable a un cerebro para convertirse en adicto a alguna droga o, por el contrario, dificultan la eficiencia de los tratamientos en contra de la adicción. Entre los polimorfismos que se han descrito son de interés los genes que codifican para las enzimas hepáticas citocromo P450, ya que estos polimorfismos modifican la vulnerabilidad para la adicción al tabaco, al alcohol y a la heroína. Es menester considerar la influencia genética en la adicción puesto que las variaciones a este nivel harán responder diferencialmente al tratamiento a personas con el mismo tipo de adicción. Por ello, hay que enfatizar el uso individualizado de la terapia. Por último, planteamos que quienes buscarán con mayor probabilidad el uso de una droga son quienes presentan una enfermedad psiquiátrica de fondo, así que la adicción representa sólo una parte de una enfermedad dual o comorbilidad. En este contexto, la hipótesis de la automedicación sugiere que los pacientes buscan la droga con el fin de controlar su patología inicial. Esta revisión busca integrar la interacción entre el cerebro, las drogas y los genes, pero no pretende ser exhaustiva. Nuestro interés es dar un panorama al lector sobre cómo estos tres mundos convergen, para entender cómo ocurre esta enfermedad y tratarla diferencialmente entre los individuos. <![CDATA[<b>Autoevaluación</b>]]> http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0185-33252010000500012&lng=pt&nrm=iso&tlng=pt The pleasant sensation experienced when, for example eating or having sex is regulated by the motivation-rewarding system. This rewarding sensation makes the subject to repeat the behavior in order to obtain the reinforcer once more. This system can be corrupted by drugs of abuse by triggering an «intense feeling of pleasure» and inducing plastic changes. In normal conditions, a natural reinforcer is a stimulus generating a benefit to the organism. For example, food will provide energy and structure among many other benefits. Sex, in turn, accomplishes the function of giving new beings to the species and to create boundaries between subjects to generate groups and culture. Due to these facts, it is crucial to reinforce this kind of behaviors. They are crucial for the subject's life. In contrast, drugs do not produce any benefit to the subject or group. Although in ancient times human beings used drugs as a means to develop and practice their mysticism, such practice is no longer associated with the use of drugs. With the exception of present time aboriginal communities, none of the regular users in our countries consume drugs with ritual-mystical purposes. Hence, we have to accept that drugs are of no use for human beings. They do not help us as species to have more adapted, intelligent or developed subjects in our communities. However, their ability to stimulate the rewarding system makes them popular and dangerous to the individual's health and life. The motivation-rewarding system is regulated by numerous neurotransmitters, among them dopamine, that is released in the nucleus accumbens (NAc) and synthesized by the neurons located in the ventral tegmetal area (VTA). There are other substances that modulate the activity of the dopaminergic neurons in the VTA, such as serotonin, acetylcholine, gamma-aminobutyric acid (GABA) and glutamate. The activation of the VTA and its consequent activation of the NAc enhance the release of neuromodulators such as endorphins and endocannabinoids, thus generating the subjective sensation of pleasure. All these interactions trigger the activity of memory systems generating a memory trace encoding the characteristics of the substance or behavior causing pleasure. This occurs in the context that the brain accepts these substances or behaviors as beneficial to the organism. The punishment system is also a very important system working in tight communication with the pleasure system. Fear is one of the most critical adapting behaviors for any subject in the animal kingdom. Fear helps us to avoid dangerous stimulus and behaviors. There is also pleasure involved in escaping this kind of situations. It seems like there is an interaction between the motivation-rewarding and the punishment systems. As a result, there is a balance at times in favor of pleasure, at times in favor of punishment depending on the quality of the stimulus. This balance gives the valence to the emotion triggered by the stimulus. A stimulus with a positive valence will increase the probability of exhibiting the behavior displayed to obtain it, while a stimulus with a negative valence will increase the probability of exhibiting the behavior displayed to avoid it. In this context, the so-called non-natural reinforcers such as drugs of abuse act directly on the pleasure system. For example, nicotine acts on the nicotinic receptor of ACh, alcohol, on the receptor of GABAa and glutamate (NMDA), marihuana on the endocannabinoid receptor (CB1 R), located in the motivation-rewarding system triggering an «intense sensation of pleasure». However, two main shortcomings make drugs of abuse dangerous: first, their effect is short and, second, they do not convey any beneficial effect to the organism whatsoever. Brain mechanisms not very well defined detect this lack of benefit; hence, the motivation-rewarding system reduces its response by means of at least two plastic changes, reducing the availability of receptors (epigenetic changes induced by the drug) and by increasing the activity of the punishment system to maintain the balance. As a result, the subject does not experience the same pleasure with the same dose of the drug. In the clinic we call this phenomenon tolerance. If the individual insists in pursuing the same intensity of pleasure, he/she has to consume more of the drug, forcing the brain to strengthen its plastic changes. In this context, we can say that these systems are defending themselves against the action of the drug. Then, why do subjects insist in pursuing the effect of drugs? Very likely because the substrate of the subject's disorder resides anywhere in the brain but in the pleasure system. If so, this indicates that drug addiction is a disorder caused by another disease, very likely a psychiatric one. Several factors contribute to generate drug addiction, i. e. social, psychological and genetic. Genes contribute in different ways to generate the subject's vulnerability to suffer an addiction. A gene mutation (alteration in genetic information) or a given polymorphism (the existence of multiple alleles of a gene in a population) can produce a dysfunctional protein or alter its normal levels. Such changes may make some individuals vulnerable to the initial use of drugs of abuse. However, those genes facilitating adjustments in the motivation-rewarding system that occur after the repeated consumption of drugs of abuse seem to be functioning normally, as we can infer from the development of tolerance. The heritability of these genes, making subjects vulnerable to addiction, has been studied in many ways, including studies of families, adoptees, and twins (monozygotic and dizygotic). From these studies it has been possible to calculate the heritability index, a measure which indicates how much variance of a trait in a specific sample is associated to genetic factors and how much to the environment. The heritability index has a range from 1, meaning the maximum genetic influence, to 0, meaning the maximum environment influence. At present, a significant number of genes have been involved in facilitating addiction to drugs, and also very important, to the response to treatment for rehabilitation. The expression of the genes is regulated by a series of processes called epigenesis. Epigenetic changes can be a result of the interaction between genes and environment. This interaction results in chemical processes that modify chromatin structure. For example, cytosine nucleotide methylation causes chromatin condensation, which interferes with gene transcription; hence, the protein encoded by this gene will be reduced, and the function in which it participates will be altered. As an example, when the methylation of the gene encoding for the glucocorticoid receptor occurs in rats, it reduces the bioavailability of this receptor and increases the release of corticosterone when rats are stressed. At the behavioral level, rats seem to be more stressed most of the time as compared with rats without methylation of this gene. Almost every stimulus in the environment is a potential promoter of epigenesis. Epigenesis is important to occur, since it is an adaptive response of the organism to the environment. It seems like the switches of the genes are turned on or off according to environment circumstances. These genetic changes will be ultimately expressed as plastic changes pursuing the right adaptation of the subject to the environment. Parental care seems to be one crucial contributor to these epigenetic modifications. For example, when a mother-rat provides poor care (feeding, grooming, and physical contact) to its litter during the neonate period, facilitates the methylation of genes, as it has been proved for the glucocorticoid receptor. These changes generate subjects with poor stress management and less capability for learning. Likewise, it makes them susceptible to drug addiction. These results highlight the importance of parental care as provider of a healthy environment, which is modeling the expression of their genes, hence their behavior.<hr/>La definición de adicción propuesta por la Organización Mundial de la Salud, dicha de manera sucinta, indica que es una enfermedad cerebral que provoca una búsqueda compulsiva de la droga y su uso, a pesar de las consecuencias adversas que ésta provoque. La fisiopatología de la enfermedad sugiere una interacción entre mecanismos cerebrales, cambios genéticos y medio ambiente. El objetivo de este artículo es discutir la evidencia que existe sobre los sistemas cerebrales que son afectados por las drogas, qué genes participan y cómo el medio ambiente tiene una participación crucial para generar esta enfermedad. Discutiremos tres secciones: el cerebro, las drogas y los genes. La primera trata sobre cómo el cerebro responde ante estímulos reforzantes y cómo estos sistemas cerebrales promueven que el individuo repita la conducta que lo llevó a adquirir el reforzador originalmente, para obtenerlo de nuevo. A este sistema se le denomina sistema de motivación-recompensa. Este sistema responde muy activamente ante reforzadores naturales (estímulos que buscan preservar la vida del individuo), pero también a reforzadores no naturales. En este grupo de estímulos están las drogas de abuso. El sistema de motivación-recompensa está modulado por diversas estructuras subcorticales y corticales que incluyen un sistema de castigo. Estos sistemas util izan una gran diversidad de neurotransmisores y neuromoduladores que inducirán una sensación de placer ante la presencia del estímulo reforzante. Todas las drogas de abuso provocan un efecto sobre los receptores y sobre los transportadores de los neurotransmisores, al igual que sobre las enzimas que participan en la síntesis y degradación de estos mediadores químicos. El uso repetido de la droga modifica así estructural y funcionalmente al cerebro. Estos cambios plásticos desarrollados en el sistema de la motivación-recompensa y también en el de castigo, provocan un nuevo balance entre ellos que lleva al individuo a un estado de alostasis, en el cual la droga se convierte en una necesidad. En otro artículo haremos una reseña sobre drogas lícitas e ilícitas; sus efectos, sus sitios de acción y las consecuencias adversas de su uso. La última sección versará sobre la genética: definimos los conceptos de gen y alelo, de mutación y polimorfismo, heredabilidad y epigenética, a fin de entender qué hace a un individuo vulnerable a la adicción de una droga de abuso. Si bien para la adicción existe una contribución ambiental, la contribución genética es importante. Esta contribución no es igual para las diferentes drogas. La cocaína y los opiáceos, no solamente son las drogas más adictivas, sino también las que mayor contribución genética tienen en comparación con otras (v. gr. nicotina, alcohol o marihuana). Los polimorfismos en diversos genes hacen vulnerable a un cerebro para convertirse en adicto a alguna droga o, por el contrario, dificultan la eficiencia de los tratamientos en contra de la adicción. Entre los polimorfismos que se han descrito son de interés los genes que codifican para las enzimas hepáticas citocromo P450, ya que estos polimorfismos modifican la vulnerabilidad para la adicción al tabaco, al alcohol y a la heroína. Es menester considerar la influencia genética en la adicción puesto que las variaciones a este nivel harán responder diferencialmente al tratamiento a personas con el mismo tipo de adicción. Por ello, hay que enfatizar el uso individualizado de la terapia. Por último, planteamos que quienes buscarán con mayor probabilidad el uso de una droga son quienes presentan una enfermedad psiquiátrica de fondo, así que la adicción representa sólo una parte de una enfermedad dual o comorbilidad. En este contexto, la hipótesis de la automedicación sugiere que los pacientes buscan la droga con el fin de controlar su patología inicial. Esta revisión busca integrar la interacción entre el cerebro, las drogas y los genes, pero no pretende ser exhaustiva. Nuestro interés es dar un panorama al lector sobre cómo estos tres mundos convergen, para entender cómo ocurre esta enfermedad y tratarla diferencialmente entre los individuos.