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versão impressa ISSN 0185-3325
Salud Ment vol.35 no.2 México Mar./Abr. 2012
Disordered eating behaviors and binge drinking in female highschool students: the role of impulsivity
Conductas alimentarias de riesgo y consumo escesivo de alcohol en mujeres estudiantes: el papel de la impulsividad
René Ocampo Ortega,1 letza Bojorquez Chapela,2 Claudia Unikel Santoncini3
1 Hospital Naval de Veracruz. Secretaría de MarinaArmada de México. Veracruz, Ver.
2 Departamento de Estudios de Población. El Colegio de la Frontera Norte, Tijuana, BC.
3 Dirección de Investigaciones Epidemiológicas y Psicosociales, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz.
Dra. Claudia Unikel Santoncini,
Dirección de Investigaciones Epidemiológicas y Psicosociales,
Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz,
Calz. MéxicoXochimilco 101, San Lorenzo Huipulco, Tlalpan, 14370, México, DF.
Recibido primera versión: 23 de septiembre de 2010.
Segunda versión: 12 de abril de 2011.
Tercera versión: 29 de agosto de 2011.
Aceptado: 31 de agosto de 2011.
It is widely accepted that psychiatric comorbidity can increase the severity, chronicity, and treatment resistance of psychiatric disorders. In various studies worldwide, it has been estimated that the prevalence of alcohol use disorders in women with disordered eating behaviors (DEB) is situated at between 2.9 and 48.6%. It is worth noting that previous studies have not considered the analysis of the variables that could explain the comorbidity between DEB and alcohol use in adolescents, such as impulsivity, which is the key variable for explaining this comorbidity. On the other hand, most studies have addressed the adult population in psychiatric hospitals or people with eating disorders (ED) or alcohol use disorders. It is considered that those subjects have already developed psychiatric comorbid disorders. Impulsivity could be an unspecific trait that aggravates the psychiatric condition of a determined person and it is therefore more likely for that person to seek specialized care. According to the above, the role of impulsivity in the comorbidity of ED and alcohol use might not be similar to that of the general population, mostly among those who have not yet developed a whole clinical syndrome. Therefore, we consider that it is important to clarify the involvement of impulsivity in the comorbidity between disordered eating behaviors (DEB) and binge drinking (BD) in high school students. It is also crucial to analyze the association between impulsivity and the coexistence of DEB and binge drinking (BD) in female students aged between 15 and 19 years at public high schools in the State of Mexico.
Data for this study were drawn from the Project entitled "Prevalence and Factors Associated with Disordered Eating Behaviors in Adolescent Women with Different Levels of Urbanization and Migration Intensity" (CONACyTSEP200446560). The design for this study is crosssectional and analytical. A sample of 2357 female students at 11 public high schools in the State of Mexico was randomly selected during the 20062007 school year. For data collection for this project, a questionnaire was used that included sociodemographic variables, the Plutchik Impulsivity Scale (PIS), the Brief Questionnaire to Measure Risky Eating Behaviors (BQREB), and the questions on alcohol use included in the Questionnaire of Surveys on Substance Use in Students in Mexico (2003 version). Data were analyzed with the STATA version 10 survey function.
Impulsivity was associated with the coexistence of DEB and BD (U=224427; p<0.01). The 3.5% of female students with impulsivity presented DEB and BD together vs. 0.6% who did not; 19.6% of female students with impulsivity presented one of the two behaviors vs. 7.8% without this trait. Impulsivity was associated positively and significantly with the coexistence of DEB and BD (t=3.8; p<0.01), regardless of socioeconomic variables, such as the father's educational attainment, the mother's educational attainment, and the number of services in the household.
The results of this paper indicate a statistically significant association between impulsivity and the coexistence of DEB and BD. This means that there is a greater percentage of coexistence of DEB and BD in female high school students considered to be impulsive in comparison with adolescents without this trait. This occurs regardless of socioeconomic variables, such as the father's educational attainment, the mother's educational attainment, and the number of services in the household. Future research should establish the role of other variables such as depression and examine the association of impulsivity with socioeconomic variables.
Key words: Impulsivity, disordered eating behaviors, binge drinking, students, Mexico.
En términos generales, se acepta que la comorbilidad psiquiátrica puede incrementar la gravedad, la cronicidad y la resistencia al tratamiento de los trastornos psiquiátricos. En diversos estudios en todo el mundo se ha estimado que la prevalencia de trastornos por consumo de alcohol en mujeres con conductas alimentarias de riesgo (CAR) se sitúa entre el 2.9 y el 48.6%. Es importante señalar que los estudios anteriores no han considerado el análisis de las variables que podrían explicar la comorbilidad entre las CAR y el consumo de alcohol en los adolescentes, tales como la impulsividad, que es la variable considerada como la más importante para explicar dicha comorbilidad. Por otro lado, la mayor parte de la literatura ha estudiado a población adulta en hospitales psiquiátricos o a sujetos que ya han cumplido con los criterios diagnósticos de los trastornos de la conducta alimentaria (TCA) y de los trastornos por uso de alcohol. Se ha considerado que dichas poblaciones ya han desarrollado trastornos psiquiátricos comórbidos y que la impulsividad puede ser un rasgo inespecífico que agrava la situación psiquiátrica de una persona y que de esa forma sea más probable que acuda a una institución hospitalaria. Por lo tanto, es posible que la participación de la impulsividad en la comorbilidad entre los TCA y el consumo de alcohol no sea similar en la población general, sobre todo en la que no ha desarrollado los trastornos aún. Por lo tanto, consideramos importante aclarar la participación de la impulsividad en la comorbilidad entre las conductas alimentarias de riesgo (CAR) y el consumo excesivo de alcohol (CEA) en la población general y especialmente en aquellos sujetos en riesgo de presentar estos trastornos. Para ello se consideró importante analizar la asociación entre la impulsividad y la coexistencia de las conductas alimentarias de riesgo y el consumo excesivo de alcohol en estudiantes de sexo femenino de entre 15 y 19 años en escuelas públicas del Estado de México.
Los datos para este estudio fueron obtenidos del Proyecto "Prevalencia y Factores Asociados a Conductas Alimentarias de Riesgo en Mujeres Adolescentes en Localidades con diferente Nivel de Urbanización e Intensidad de Migración" (CONACyTSEP200446560). El diseño del estudio es transversalanalítico. La unidad de análisis fueron las estudiantes de sexo femenino entre 15 y 19 años de edad en instituciones educativas públicas de nivel medio superior en el Estado de México. Para la selección de las estudiantes, se utilizó un muestreo aleatorio estratificado. La muestra consistió en 2357 estudiantes de 11 escuelas públicas en el Estado de México durante el año escolar 20062007. Para la recolección de datos se empleó un cuestionario que incluía variables sociodemográficas, la Escala de Impulsividad Plutchik, el Cuestionario Breve de Conductas Alimentarias de Riesgo, y las preguntas sobre el consumo de alcohol, incluidas en el cuestionario de estudiantes (versión 2003) de las encuestas sobre consumo de sustancias en estudiantes de México. Los datos fueron analizados con la función survey del programa estadístico STATA versión 10 con una ponderación de la muestra que correspondió a la probabilidad de selección debido al nivel de marginación y estatus migratorio. Para determinar la asociación entre la impulsividad y la coexistencia entre las CAR y el CEA, se realizó un análisis de regresión ordinal.
La impulsividad se asoció con la coexistencia entre las conductas alimentarias de riesgo y el consumo excesivo de alcohol (U=224427, p<0.01). El 3.5% de las estudiantes con impulsividad presentaron CAR y CEA de manera conjunta vs. el 0.6% que no cumplieron con dicha definición, mientras que el 19.6% de las estudiantes con impulsividad presentaron una de las dos conductas vs. 7.8% sin dicho rasgo. La impulsividad se asoció de manera positiva y significativa con la coexistencia CAR & CEA (t=3.83; p<0.01), de manera independiente a las variables socioeconómicas como la escolaridad del padre, la escolaridad de la madre y el número de servicios en la vivienda.
Los resultados de este trabajo indican una asociación estadísticamente significativa entre la impulsividad y la coexistencia de CAR y CEA. Lo anterior significa que hay un porcentaje mayor de la coexistencia de CAR y CEA en las estudiantes que cumplieron la definición operacional de impulsividad en comparación con las estudiantes sin dicho rasgo, de manera independiente a las variables socioeconómicas como la escolaridad del padre, la escolaridad de la madre y el número de servicios en la vivienda. Los resultados del presente estudio muestran que la impulsividad está asociada con una serie de conductas que pueden incrementar el desarrollo de un TCA comórbido con un trastorno por consumo de alcohol, y por lo tanto, sugieren un peor pronóstico para las adolescentes incluidas en el estudio. Lo anterior plantea la necesidad de detectar a los sujetos en riesgo de desarrollar ambos trastornos y su canalización a los servicios de salud especializados. Queda pendiente establecer el papel de otras variables como la depresión, y estudiar la asociación entre la impulsividad con las variables socioeconómicas mencionadas.
Palabras clave: Impulsividad, conductas alimentarias de riesgo, consumo excesivo de alcohol, estudiantes, México.
It is widely accepted that psychiatric comorbidity can increase the severity, chronicity, and treatment resistance of psychiatric disorders.1 In various studies worldwide, it has been estimated that the prevalence of alcohol use disorders in women with disordered eating behaviors (DEB) is situated at between 2.9 and 48.6%.2,3 In this regard, some studies found that, among adolescents with bulimia nervosa, substance use is related to other disordered behaviors, such as suicide attempts, stealing, and compulsive sexual conduct.4,5 It has also been found that the severity of alcohol use in patients with anorexia nervosa predicts their mortality.6
Studies on the US general population7 indicate that 36% of adolescent women with "abnormal eating behaviors" were binge drinkers (BD) in comparison with adolescent women without these behaviors (18.1%) (Odds ratio [OR], 2.7; 95% confidence interval [95% CI], 2.33.2). The literature in Mexico that has studied this association is scarce.8,9 In 2002, Gutierrez et al.9 studied the relationship between DEB and BD in 286 adolescent women in Mexico City. Among the results of this study, it was found that adolescents with DEB consumed five or more drinks of alcohol on each occasion more frequently (37.1 vs. 14%; x2 = 21.46; p<0.01) than those who did not present this risk. Recently, in a sample of adolescent students in the State of Mexico, Unikel et al. (2011) found that BD during the last 12 months was nearly four times greater in high school students at risk of having disordered eating than in high school students without this risk, with no differences in stratifying for marginalization levels.
In general, it is worth noting that the aforementioned studies did not consider the analysis of the variables that could explain the comorbidity between DEB and alcohol use disorders in adolescents, such as impulsivity, which is the most important variable for explaining this Comorbidity.1,1013 Impulsivity was defined by Chamberlain & Sahakian14 as "a multiplicity of behaviors and responses that are premature, inappropriate, and incomprehensible and that frequently lead to damaging and undesirable results". These authors describe various cognitive domains linked to impulsivity, such as the ability to accumulate and evaluate information prior to arriving at a decision (reflection), the ability to opt for longterm rewards instead of small, shortterm rewards (deferred gratification), and the ability to suppress motor responses (response inhibition).
As mentioned earlier, most of the literature has studied the adult population in psychiatric hospitals or subjects who have already met the diagnostic criteria for eating disorders (ED) and substance use disorders. Welch & Fairburn15 considered that these populations have already developed comorbid psychiatric disorders and that impulsivity can be an unspecific trait that aggravates the psychiatric situation of a person meaning that the subject is therefore more likely to seek hospital care. It is therefore important to clarify the involvement of impulsivity in the comorbidity between DEB and BD in a different setting to the mental health hospital.
On the other hand, it is essential to consider that variables such as socioeconomic level can exert an influence on the emergence of substance use disorders and DEB. With respect to the former, a higher occurrence of BD has been found in US and LatinAmerican adolescent populations in those with a high socioeconomic level.1618 Regarding DEB, although mixed results have been found, studies in Mexico and in other countries have found that their occurrence is higher among subjects with a high socioeconomic level.19,20
In this respect, we consider that it is crucial to study impulsivity as a factor associated with the occurrence of DEB and BD, regardless of socioeconomic level. This is particularly important in populations that have not completely developed psychiatric disorders, yet who are an at risk population, such as high school students. It is important to consider that people with DEB can be considered high risk groups for the development of ED. These subjects experience behavioral and cognitive manifestations that could affect their psychosocial functioning, and can also be affected by comorbid illnesses, such as alcohol use disorders.1921 On the other hand, BD in adolescence can increase the risk of developing alcohol abuse or dependence and of progression to other substances.2226 We therefore thought it was important to conduct a study in which the link between impulsivity and the coexistence of DEB and BD were analyzed in female high school students in the State of Mexico.
Data for this study were drawn from the project entitled "Prevalence and Factors Associated with Disordered Eating Behaviors in Adolescent Women with Different Levels of Urbanization and Migration Intensity" (CONACyTSEP200446560). The project was approved by the Ethics and Research Committee from the National Institute of Psychiatry Ramón de la Fuente Muñiz.
The study design is crosssectional and analytical. The unit of analysis comprised female students aged between 15 and 19 years at public high schools in the State of Mexico. For the selection of students, we utilized a stratified, randomized sampling described previously in other articles.27
For data collection for this project, we used a questionnaire that included sociodemographic variables, the Plutchik Impulsivity Scale (PIS), the Brief Questionnaire to Measure Risky Eating Behaviors (BQREB), and the questions on alcohol use included in the Questionnaire of Surveys on Substance Use in Students in Mexico (2003 version).
In this study, we included age as a sociodemographic variable, and socioeconomic variables such as the number of household services and parents' educational attainment, because in previous studies an association had been found between these variables and impulsivity28,29 and between DEB and alcohol userelated disorders.1618 In the case of socioeconomic variables, the majority of studies have found that the higher the academic level of the head of the family (an approximation of the socioeconomic level used in Mexico),30 the greater the frequency of DEB19 and the greater the alcohol use in Mexican adolescents.16,18 It is important to consider that by solely including one socioeconomiclevel indicator, a misleading image could be created of the social conditions in which the population grew up.17 We therefore decided to include household services together with parental educational attainment in the model analyzed.
The PIS developed by Plutchik & Van Praag31 evaluates the tendency to engage in impulsive behaviors that reflect a possible loss of control. This scale was validated in Mexican high school students in urban as well as in rural populations in the State of Mexico by Unikel et al.*
Factorial analysis yielded a factor that explained the 36.13% variance (Cronbach's alpha, 0.72). In this study, high school students were considered in the group of high impulsiveness if their score on this questionnaire was found to be at one standard deviation (SD) above the mean of the population studied.
The BQREB was drawn up in 1997 to identify DEB in young Mexican women based on ED DSMIV32 diagnostic criteria.33 The questionnaire was previously validated in high school students in the State of Mexico.* Factorial analysis yielded three factors that explained the 62.9% variance. The behaviors mentioned were evaluated during the three months prior to the application of the BQREB33 and it was considered that adolescents had these behaviors if they obtained a score of >10.
To evaluate alcohol use in high school students, we used the Smart Student Questionnaire (designed in 1980). Originally in English, the questionnaire was translated into Spanish and validated by MedinaMora et al. in Mexican students.34 This questionnaire contains central questions such as substance use recommended by the World Health Organization (WHO) and has been utilized in surveys on substance use in students in Mexico over the past 20 years.18,35,36 The questionnaire includes queries on alcohol use throughout the lifetime of the respondent, in the previous 12 months, and in the previous 30 days. This study regarded binge drinking as the consumption of five or more drinks on one occasion with a frequency of more than once a month.
Data were analyzed with the survey function of the STATA software version 10 with a sample weight that corresponded to the probability of selection due to marginalization level and migratory status.
Data are given in percentages for categorical variables with 95% confidence intervals (95% CIs). Continuous variables are presented as means and SDs. For bivariate analysis, the variables of age (with the categories of 1617 years, and 17 or more years), father's and mother's educational attainment (with the categories "less than secondary school," and "secondary school or more"), number of household services ("fewer than seven services," or "more than seven services"), and impulsivity were compared with the "coexistence of disordered eating behaviors and binge drinking" variables. We created a variable called "coexistence of disordered eating behaviors and binge drinking," which had an ordinal measurement level. It comprised the following categories:
1. coexistence of disordered eating behaviors and binge drinking (DEB & BD), made up of high school students who fulfilled the operational definition of both problems (n=21);
2. disordered eating behaviors or binge drinking (DEB/BD) when the high school students met the definition of only one problem (n=206), and 3. no condition: high school students who at the time of the survey had not consumed alcohol and those who consumed fewer than five drinks per occasion with a lower frequency than that defined (monthly or annually), as well as those who scored 10 or less on the BQREB (n=1932). The statistical test selected was the MannWhitney U. In the multivariate analysis and to determine the association between impulsivity and the coexistence of DEB and BD, an ordinal regression analysis was carried out, which allowed for the formation of the dependence of a polytomic ordinal response on a set of predictors, which can comprise factors or covariables.37 The association was considered significant if p<0.05.
The total number of students who participated in the survey was 2357, with an average age of 16.28 (range 1519; SD 1.0). The remaining sociodemographic data are presented in table 1. The PIS was answered by 2272 highschool students (percentage of nonresponse: 3.6%). The mean score of this scale was 20.5, with an SD of 5.1. Given the operational definition of impulsivity, the cutoff point was established at 25.
With this cutoff point, 15.4% (95% CI, 13.817.0) of adolescents in the total sample displayed a significant impulsivity level (n = 352). On the other hand, the study found that 96 high school students (4.2% of the sample; 95% CI, 1.47.0) presented a score of >10 in the BQREB and that 173 of the high school students sampled (11.7%; 95% CI, 8.914.6) presented BD. In other words, they consumed five or more drinks on one occasion with a frequency of more than once a month. The prevalence of BD in high school students with DEB was estimated at 27.3% (n=21; 95% CI, 17.337.2). This percentage was significantly greater that that found in high school students without this behavior, estimated at 11.2% (n=150; 95% CI, 9.512.8) (χ2, 17.5; p<0.01).
The bivariate analysis showed that impulsivity was associated with coexistence between DEB and BD (U=224427; p<0.01). A total of 3.5% of highschool students who complied the operational definition of impulsivity presented DEB & BD in a combined manner, compared with 0.6% (n=10) of high school students who did not meet this definition. On the other hand, 19.6% (n=62) of highschool students with impulsivity displayed some of the conditions (DEB/BD) in comparison with 7.8% (n=127) of highschool students without these traits (table 2).
Lastly, the bivariate analysis showed that having a mother and father who were high school graduates together with a greater number of household services, was significantly associated with impulsivity (data not shown), as well as with the coexistence of DEB and BD. We therefore decided to control by means of these variables as potential confounders in the ordinal regression analysis (table 3). In this analysis, we found a positive and statistically significant association between household services and the coexistence of DEB and BD (t= 5.2; p<0.01) and between impulsivity and the coexistence of DEB and BD (t=3.8; p=<0.01). In other words, high school students with impulsivity showed a greater likelihood of displaying this coexistence, regardless of household services.
The results of this paper indicate a statistically significant association between impulsivity and the coexistence of DEB and BD. This means that there is a greater percentage of coexistence of DEB and BD in high school students considered to be impulsive in comparison with high school students without this trait, regardless of socioeconomic variables, such as the father's educational attainment, the mother's educational attainment, and the number of services in the household.
The association between impulsivity and the presence of DEB is an issue that has been approached previously in studies conducted in the US, Italy, and Australia.11,12,38 Most of these studies emphasize the association between this trait and EDs such as bulimia nervosa and binge eating disorder, in which the spontaneous component of impulsivity plays an important role in uninhibited behavior and loss of control during episodes of excessive eating, above all in the negative affect response.12,39 On the other hand and in terms of alcohol use, the novel, social aspects of first substance use can initially appear attractive, while repeated use in large amounts increases the value of the substance in itself. This point, together with the deterioration of the brain's inhibitory function that contributes to uninhibited behavior and the inability to suspend this use, can translate into more serious addictive behavior in clinical terms which, in turn, can be accompanied by negative consequences for the health of these high school students.12,40 Finally, once the reward pathways have been activated, other rewardimplying behaviors could acquire greater relevance, as in the case of food, leading to problems regarding the ingestion of food.11
In a previous study, Welch & Fairburn15 suggested that in hospitalized populations with EDs, alcohol use might not be a response to an impulsive action, but could instead be related to other factors (major depressive disorder, anxiety disorders, personality disorders, etc.). However, the results of this study in student populations show that impulsivity is associated with a series of behaviors that could increase the possibility of presenting an ED comorbidity with an alcohol use disorder in the future and, therefore, suggest a possibly worse prognosis for the highschool students included in this study. This suggests the need for screening programs at school and in the general population in order to identify atrisk subjects for both disorders, for proper referral to available health services. It should be noted that early management of these disorders could prevent complications at the physical and mental level as well as improving prognosis.1
In the study we decided to use household services as an indicator of the socioeconomic conditions of the sample, which was positively associated with the coexistence of DEB and BD. In this respect, there are previous studies that have found an association between socioeconomic status and DEB, with the possibility of increased exposure to an aesthetic ideal and greater accessibility of services and products for weight loss.20 With regard to alcohol consumption, this might be more common in the upper socioeconomic strata since people in these strata may regard alcohol consumption as a cultural norm and because they are able to afford it.16,17
In relation to study limitations and despite possessing a general population sample one should be cautious about generalizing the results. The sample of high school students in the State of Mexico who have access to studying high school probably displays characteristics that are different from subjects without this access. On the other hand, this study did not include males, so the relationship between study variables cannot be generalized to this population. Lastly, the study design does not show the time frame of the variables,41 although the literature indicates that impulsivity is more a predisposing factor than a consequence of DEB or BD.11,42,43
In conclusion, impulsivity is associated with the coexistence of DEB and BD in a randomized sample of adolescent students. The role of other variables such as depression and studying the association between impulsivity with socioeconomic variables has yet to be established.
The authors wish to thank the Public Education Ministry of the State of Mexico and personnel at the schools in which this study was conducted, as well as Fátima GarcíaCastro for her participation in the various stages of this project.
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