Stability and change of antisocial behavior in children and adolescents : the role of neurobiological factors

Aggressive behavior has long been a major concern in our society. There is a growing consensus that disruptive behavior disorder (DBD) originates from the interaction of biologically based child characteristics with non-optimal characteristics of the child's environment. In this thesis, we investigated neurobiological correlates of aggression and the role they play in the stability of antisocial behavior and/or in changes that occur in that behavior. We did this by focusing on the relationship of aggression to cortisol and testosterone in a low socioeconomic status (SES) population-based sample, and on the relationship of aggression to cortisol and measures of the autonomic nervous system (ANS), i.e. heart rate (HR) and skin conductance level (SCL), in a sample of referred DBD children. In addition, the role of some psychological and family characteristics in stability and change was examined, although these correlates occupy a very modest place in this thesis. Within the low SES male adolescents sample, it appeared that, although we provide some evidence that cortisol and testosterone are correlates of aggressive and antisocial behavior, the relationship was not consistent with and in contrast to what is known from literature. We suggest that this may be due to the type of participants that were studied. Furthermore, in correspondence with the finding from previous studies, we found that antisocial behavior was relatively stable in a sample of severely disturbed DBD children. There was, however, a large variance among the outcome for adolescents. When outcome was defined in terms of DBD diagnosis, living status, delinquency, school attendance, and smoking behavior, 38% had a positive outcome and 34% had a poor outcome. Moreover, in a sample of referred DBD children, SCL in particular was found to have a predictive influence on both the effect of treatment and the stability of antisocial behaviors in adolescence. Low SCL is suggested to be a marker of fearlessness. A lack of fear would predispose children to antisocial and violent behavior because low fear of socializing punishment in childhood would contribute to poor fear conditioning and lack of conscience development. In addition, social conditioning plays a central role in behavior therapy. Difficulty in social conditioning due to fearlessness thus would result in low treatment effect and in the persistence of antisocial behavior