Neurobiological correlates of aggression and emotion regulation in children and adolescents

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Aggressive and antisocial behaviour is associated with impaired emotion regulation and neurobiological alterations that are reflected on the level of autonomic as well as central nervous system functioning. Recent research on central autonomic control – as posited in the neurovisceral integration model – indicates associations between autonomic nervous system (ANS) activity and functional and structural brain correlates. An overlap of the central autonomic network (CAN) with brain regions involved in emotion regulation highlights the relevance of ANS measures in research on emotion regulation and aggression. The main aim of this thesis was to investigate and gain more insight into neurobiological correlates of aggression and emotion regulation in children and adolescents. First, we examined the relationship between resting ANS activity and aggression in more detail than has been done before. We therefore included a comprehensive assessment of ANS activity with two measures of general ANS activity (heart and respiration rate) and two measures capturing parasympathetic nervous system (heart rate variability) and sympathetic nervous system (pre-ejection period) activity separately, while considering relevant covariates such as smoking. A further sub aim was to gain more clarity on the best approach for linking psychopathology and neurobiology. Recent findings on a general psychopathology factor suggest that a dimensional approach captures psychopathology better than a categorical approach. Thus, we chose to compare two analysis approaches: a categorical (chapter 2) – based on DSM-5 – and a dimensional approach (chapter 3). The second aim of the thesis was to investigate functional brain correlates of implicit-controlled emotion regulation in individuals with and without conduct disorder (CD) (chapter 4). The third aim of the thesis was to investigate the relationship between resting heart rate variability and brain structure in female CD patients compared to typically developing adolescents (chapter 5). The findings presented in this dissertation advance the knowledge on the neurobiology of aggression and emotion regulation in children and adolescents. In line with recent evidence, the presented studies suggest that resting ANS activity, especially heart rate, might not be as strongly correlated with antisocial behaviour as previously assumed. In addition, the novel finding of higher respiration rate in female CD suggests that this measure should be further considered in future research – with a particular focus on its potential to impact heart rate variability and emotion regulation. More research on respiration in aggressive individuals could improve current treatment modalities. Further, the result indicating that comorbid internalising disorders in female CD patients are associated with lower heart rate variability warrants additional investigation and consideration of specific treatment needs. This CD group might represent a more severe psychopathological subgroup with more pronounced emotion regulation problems. Our findings of the neural correlates of implicit emotion regulation additionally support the notion of CD being characterised by deficient emotion regulation. Moreover, we reported negative correlations between resting heart rate variability and brain structure in CAN regions, which are implicated in emotion regulation. We highlighted the relevance of smoking for emotion regulation – which has been neglected so far in the context of neurobiological research on aggression and might be an important confounding factor to consider in future studies.