Schär, Selina (2023). Child Maltreatment, the Hypothalamic-Pituitary-Adrenal Axis, and Psychopathology. (Thesis). Universität Bern, Bern

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Abstract

Findings from epidemiological studies increasingly show that adult mental disorders may have their roots relatively early in life, that is, in childhood and/or adolescence. Both genetic predisposition and adverse environmental factors are known to play a central role in the developmental trajectory of psychopathological outcomes. Among the environmental factors associated with the emergence of mental disorders are experiences of abuse and neglect early in life, collectively referred to as child maltreatment. According to the biological embedding model, such adverse early life experiences are assumed to cause biological scars – i.e., changes in essential biological systems – which in turn are thought to influence vulnerability to mental disorders later in life. More specifically, following corresponding adverse experiences, alterations in biological systems centrally involved in the processing of stress and emotional regulation – including the hypothalamic-pituitary-adrenal (HPA) axis – have been suggested. As a result, extensive research has been conducted to examine associations between child maltreatment experiences and long-term changes in the functioning of relevant biological systems, including studies of changes in cortisol secretion – the main effector hormone of the HPA axis. To date, however, mostly inconsistent results have been observed with regard to cortisol metabolism. The aim of the present thesis was therefore to systematically investigate the biological embedding of altered HPA axis activity following child maltreatment. Particular attention was paid to the potential moderating/interfering influence of psychopathology. This because, on the one hand, child maltreatment experiences are strongly associated with mental disorders, and on the other hand, altered cortisol secretion has been observed in patients with mental disorders as well. Accordingly, in a first step, the potential association between the experience of child maltreatment and HPA axis functioning, including different measures of cortisol secretion (i.e., cortisol assessed in the context of the circadian rhythm, cortisol assessed in response to awakening, in response to the perception of a stressor, in response to pharmacological challenges, as well as cumulative measures of cortisol secretion), was thoroughlyinvestigated by means of a comprehensive systematic review and meta-analysis. In a second step, differences in pituitary gland volume (PGV) – an approach to assess long-term HPA axis activity – between adolescents engaging in non-suicidal self-injury (NSSI) and healthy controls, were examined. NSSI represents a psychopathological behavior that typically develops/exacerbates during periods of elevated stress and that has been found to be strongly associated with child maltreatment experiences. In this context, particular attention was paid to whether potential structural changes could be better explained by child maltreatment or psychopathology. The meta-analytic study conducted revealed a blunted cortisol stress reactivity in individuals exposed to child maltreatment compared to those without such experiences. Importantly, although less pronounced, participants with a history of child maltreatment who did not report a mental disorder at the time of measurement likewise showed an attenuated cortisol stress response. No overall differences, however, were found in any of the other measures of HPA axis activity (with the exception of evening cortisol). With regard to the second study, no evidence was found for overall volumetric differences in PGV between healthy control participants and adolescents engaging in NSSI, recognizing that small effect size differences could not be detected in this study. Group membership, however, significantly interacted with age in predicting PGV. In particular, while PGV increased linearly with age in healthy controls, no such association was found in NSSI patients. Child maltreatment neither explained significant variance in PGV nor interacted with age in predicting PGV. The present synopsis aims to integrate these findings into the context of the biological embedding model and discusses methodological limitations as well as considerations for the conduct of future studies.

Item Type:	Thesis
Dissertation Type:	Cumulative
Date of Defense:	14 December 2023
Subjects:	600 Technology > 610 Medicine & health
Institute / Center:	07 Faculty of Human Sciences > Institute of Psychology
Depositing User:	Hammer Igor
Date Deposited:	01 Oct 2024 15:53
Last Modified:	01 Oct 2024 15:53
URI:	https://boristheses.unibe.ch/id/eprint/5468

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