Introduction.

Behavioural alterations are a quite potent predictor for schizophrenia. Very often, apparently healthy adolescents (who will later develop schizophrenia) present altered conducts similar to those manifested by schizophrenic subjects and as predictors for the disorder.

There are studies that describe the relationship between these behavioural alterations and the features found in schizotypical personality disorder or schizophrenic symptoms. In this way, it has been established that those subjects who obtain high scores in schizotypy present more behavioural alterations.

Concretely, the different behavioural alterations have been differentially related to the positive and negative subtypes of the schizotypical personality, suggesting continuity between the nature of premorbid conducts and the adult symptoms patterns in which the illness develops. On the other hand, comparing adolescents that will later develop schizophrenia with those who will not, it has been found that the best schizophrenia predictor is a poor behavioural adjustment.

Moreover, if the teachers' reports are examined, there can be certain aspects such as the early behavioural patterns which will identify children who, for instance, will develop schizophrenia thirty years later, or even differential patterns according to the gender of the subjects.

Therefore, if we want to carry out a schizophrenia prediction according to these behavioural criteria, knowing which informants are more useful and how their opinions match among them is of a great interest. Until this moment, the majority of studies have pointed out at the ability of teachers to identify conducts that can be used to select people at risk for schizophrenia. However, having into account that numerous studies conclude that there is a lack of agreement between these and other different informants for behavioural alterations in adolescents, the importance of studying the variables that can be influencing this matter must be raised.

Following with the line of our research group a question is raised. We wonder if the presence of schizotypical personality traits makes the adolescents behaviour more ambiguous, with the consequent difficulty to define it in a coincident way from different evaluators and from themselves.

Objectives.

To analyse the influence of the schizotypical personality (assessed with the Oxford-Liverpool Inventory of Feelings and Experiences), the demographic variable gender and the interaction between them, in the discordance of different informants (parents, teachers and adolescents) when they inform about behavioural problems in adolescents (assessed with the Achenbach's scales).

Methodology.

This is an analytic transversal study that can be framed into a longitudinal study of 2 cohorts from the general population, which started on 2000 and has been then followed-up ("Psychoeducation program and early detection of schizophrenic disorders of adolescent onset").

Participants. 160 triads of parents, teachers and adolescents from 13 to 16 years old selected from 7 schools of Barcelona took part in the study.

Instruments. The three forms of the Achenbach scale for the measure of behavioural alterations were applied: Youth Self- Report, Child Behaviour Checklist/4-18 and Teacher's Report Form. These forms contain 8 scales which are invariant throughout informants: Withdrawn, somatic complaints, anxious/depressed, social problems, thought problems, attention problems, delinquent behaviour and aggressive behaviour. Some of them are grouped in second order factors: Internalizing, externalizing and total.

To evaluate the psychometrical schizotypical personality of adolescents we used the Oxford-Liverpool Inventory for Feelings and Experiences. It consists of an autoadministered inventory with 159 items that includes four schizotypical scales. The Unusual Experiences scale reflects the positive dimension of schizotypy and includes items of unusual perception aberrations and magical thinking. The Introvert Anhedonia Scale reflects the negative dimension of schizotypy and consists of items assessing restricted affect, social isolation and anhedonia. The Cognitive Disorganization Scale refers to disorganized aspects of the psychosis and it is composed of items assessing difficulties in concentration and decision-making. Finally, the Impulsive Nonconformity Scale reflects the characteristics of impulsive-type personality, social anxiety and maladjusted behaviours.

Statistical proceed.

Multiple regression analyses were carried out in order to revise the influence of the schizotypical personality, the demographic variable gender and the interaction between them as possible explicative variables, in the discordance between different informants about behavioural problems of adolescents. The dependent variable was a measure of the level of discordance between the three groups of informants.

Results.

A major discordance between informants of behavioural problems was found as schizotypy was higher. Concretely, a larger number of unusual experiences in adolescents increase the discordance for thought and internalizing problems. Discordance is also higher in aggressiveness and anxiety/depression as cognitive disorganization increases. Also, the higher the introverted anhedonia, the higher the discordance is for social problems, anxiety/depression, attention, externalizing problems, and for the total.

To finish, a high score in non-conformity impulsivity increases the discordance for attention, delinquency and aggressive problems. About the influence of gender, discordance between informants for anxiety/depression is higher for females than for males.

However, this varies when the interaction effects found are considered. In this way, a differential effect for the increase of non-conformity impulsivity and introvert anhedonia can be observed in males and females. Therefore, discordance between informants is higher when evaluating anxiety/ depression in males when non-conformity impulsivity is high. Just the opposite happens for girls. In addition, the discordance for the internalizing subscale increases just as the introverted anhedonia raises for females, but it decreases when evaluating males.

Discussion.

It seems clear that no source of data can be substituted for any other when evaluating behavioural problems in adolescents and much less when attention is centred in those adolescents who score high in schizotypy.

Specifically, when evaluating the behaviour of those subjects who score high in the positive dimension of schizotypy, the agreement between informants decreases for thought and internalizing problems; and, when the behaviour of those who are defined for a more negative schizotypy is evaluated, the agreement decreases for social problems, anxiety/ depression, externalizing and total.

Having all this into account and adding information that other authors have found related to each schizotypy subtype (which, besides, are the ones which more concordance show), some conclusions could be raised. It can be assumed as evident that schizotypical personality (and each trait type) and the subjacent conduct in these subjects can generate a difficulty in perceiving certain conducts which are not predominant in the subject, with the consequent discordance between informants. For future studies, it would be very interesting to carry out studies examined which group of informants augurs the behavioural predisposition for schizophrenia and its dimensions in the most accurately way possible.

Conclusions.

A most exact and objective method to assess behavioural problems as well-demonstrated predictor to schizophrenia, is necessary in order to select vulnerable teenagers to the illness and to develop programs of early intervention.

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