Investigating structural and functional neural correlates in children and adolescents with antisocial behavior

Abstract

Antisocial behavior is highly prevalent in young and adult populations worldwide and constitutes a major public health problem due to the huge burden on the individual as well as the significant economic burden on society. A better understanding of the underlying neurobiological mechanisms of antisocial behavior is warranted to improve current diagnostics (e.g. early detection of children at risk) and effective prevention/treatment programs. So far, neuroimaging studies have indicated neural atypicalities in youths with antisocial behavior; however, the direction and location of these brain alterations vary across studies. These ambiguities are most likely caused by the heterogeneity of the young samples with antisocial behavior studied, especially regarding sex, clinical diagnoses, and the presence of callous-unemotional traits. The central aim of this dissertation was to further the neuroscientific knowledge of antisocial behavior in children and adolescents by investigating the underlying structural and functional neurobiological characteristics, with an extra focus on possible sex differences and callous-unemotional traits. First, we examined the current neuroimaging literature, through meta-analyses, with the purpose of overcoming the heterogeneity of antisocial behavior and generating a common “overlapping” pattern of structural and functional atypicalities in youths with antisocial behavior. Secondly, the relation between callous-unemotional traits and brain structure was investigated separately for sex and independently of psychiatric comorbidities. Thirdly, this work investigated the white matter integrity within a homogenous group of girls with conduct disorder –the severe variant of antisocial behavior– in comparison to typically developing peers. This work expands our current knowledge on the structural and functional neural correlates in children and adolescents with antisocial behavior in several ways. For one, our meta-analytic results indicate a consistent pattern of gray matter reductions and hypoactivations in brain areas within the prefrontal and limbic cortex. These findings fit a recently proposed neurobiological model that connects alterations within similar brain regions with the behavioral dispositions of antisocial behavior (e.g. dysfunctions in empathy, emotional learning, and decision making). Secondly, we observed a positive relation between callous-unemotional traits and bilateral insula volume in a large international population of typically developing boys, but not in girls, independent of psychiatric disorders. This demonstrates that callous-unemotional traits have a sex-specific neurobiological basis beyond psychiatric samples. Thirdly, this work presents novel findings of white-matter integrity alterations in the body of the corpus callosum of girls with antisocial behavior, indicating possible reduced interhemispheric processing and consequent emotion processing abilities. In short, the present thesis provides original findings regarding the neurobiology of antisocial behavior in youths and emphasizes the importance of callous-unemotional traits and sex differences. Our results encourage future studies to further investigate the developmental trajectories and potential neural markers of antisocial behavior in order to enhance early detection and improve intervention programs, which could ultimately reduce antisocial behavior and delinquency in our society.