Psychobiological adaptation to childhood adversity The role of contextual and individual factors

Although childhood adversity increases risk for psychopathology, not all individuals develop negative mental health outcomes. In this thesis, we aimed to address two main questions: How do childhood adversities become biologically embedded to affect mental health? And what explains individual variability in psychobiological adaptation after childhood adversity? To this end, we summarized evidence on adversity-related alterations in the functioning of the stress systems, focusing on the hypothalamic-pituitary-adrenal axis in a narrative review in Chapter 2, and on vagal regulation in a meta-analysis in Chapter 3. We further examined in these chapters whether characteristics of childhood adversity (e.g., type, severity) and individual characteristics (e.g., age, sex, psychopathology) explain different patterns of psychobiological adaptation. In two empirical studies, we aimed to broaden knowledge on specific individual moderators at the genotypical and phenotypical level. In Chapter 4, we tested whether different allelic variants of rs1360780 of the FKBP5 gene would influence the extent to which individuals demonstrate alterations in resting-state functional connectivity in the salience network in the context of adversity. In Chapter 6, we examined whether effortful control would render toddlers more or less vulnerable to develop cortisol alterations in the context of parenting stress. As secondary aims of this thesis, we investigated what times of day would be most reliable in revealing between-individual differences in young children’s cortisol levels (Chapter 5), and provided a meta-review on the development and socialization of self-regulation from infancy to adolescence (Chapter 7). Overall, our findings point to the complexity of predicting psychobiological adaptation after adversity.