Neurobiological heterogeneity in youth disruptive and aggressive behavior

Persistent disruptive, aggressive and antisocial behavior among youth is associated with a range of negative concurrent and long-term outcomes and may result in diagnoses of oppositional defiant disorder (ODD) and/or conduct disorder (CD). In addition, these youths may present with callous-unemotional (CU) traits, which reflect a lack of empathy, disregard for others, and limited emotions. Moreover, their aggressive behaviors may be further characterized as either reactive (or impulsive), or proactive (or instrumental). Even considering these diagnostic categories and behavioral dimensions, the heterogeneity within this population of youth hampers treatment efforts as well as our understanding of underlying mechanisms. Therefore, the overall aim of this thesis was to advance our understanding of the phenotypic, (neuro)cognitive, and etiological heterogeneity of disruptive, aggressive, and antisocial behavior.
Overall, I found evidence for distinct emotion recognition difficulties among youth with CD versus youth with ODD, and among youth with high CU traits and reactive and proactive aggression versus youth with high CU traits and reactive aggression but lower proactive aggression. Moreover, my results point to genetic sharing between antisocial and aggressive behavior and localized shape alterations in the amygdala, a brain structure with a well-established role in emotion processing and aggression. Finally, I found further support for fear recognition as an intermediate phenotype linking genetics to CU traits but not (reactive and proactive) aggression. In sum, the current thesis illustrates the heterogeneity of youth showing disruptive, aggressive, and antisocial behavior, and provides support for specific cognitive, neural, and genetic correlates underlying distinct aggression-related phenotypes.