title: Resting-state, responsivity, and circadian rhythmicity: three different functional components of autonomic nervous system activity in the context of developmental psychopathology
Creators: name: Sigrist, Christine
Publisher: name: Universität Bern
Year: 2022
Subjects: subject: 610 Medicine &amp; health

description: First onset of psychiatric symptoms and disorders usually occurs in childhood or adolescence, presenting a significant portion of the burden of disease in young individuals. The disruption of physiological regulatory systems may present one patho-mechanism underlying the development of psychiatric symptoms and disorders in this age group. Altered autonomic nervous system (ANS) function has been shown to occur prior to observable clinical symptoms, and is typically characterized by an imbalance between its two branches, the sympathetic and parasympathetic nervous systems. Dysfunction of the ANS is frequently indexed by reduced vagally-mediated resting-state heart rate variability (vmHRV), reflecting parasympathetic (vagal) activity. Substantial neurophysiological evidence suggests a relationship between reduced vmHRV and psychiatric disorders characterized by impaired emotion regulation (ER). Alongside resting-state ANS activity, measures of ANS responsivity to challenge (i.e., cardiac reactivity and recovery in response and subsequent to psychological stress exposure) have been suggested as markers of ER, while existing findings on the respective relationships are mixed. Markers of cardiac vagal activity follow rhythmic pattern of circadian variation (circadian variation patterns, CVP), reaching peak levels during nighttime. Indices of CVP of ANS activity may quantify restorative physiological processes, and may be linked with the restoration of autonomic balance. CVP of ANS activity may therefore present further indices of socio-emotional regulatory capacity.

The aim of the present thesis was to investigate different markers of cardiac autonomic activity indexing different functional components of ANS activity (i.e., resting-state, responsivity, and circadian rhythmicity) in developmental psychopathology. First, potential associations between experiences of severe adversity early in life (early life maltreatment, ELM), typically associated with deficient ER, and resting-state vmHRV were investigated in a comprehensive meta-analysis. Second, cardiac responsivity to a standardized stress task was assessed as potential predictor of treatment outcome over two years in a preliminary experimental psychotherapy study. Here, heart-rate (HR) and vmHRV responsivity were used as ANS markers. In a third study, CVP of cardiac autonomic activity was analyzed in female adolescents engaging in non-suicidal self-injury (NSSI). The meta-analytic study suggested no general association between resting-state vmHRV and ELM exposure, while accompanying meta-regression analyses revealed potential patterns of association between exposure to ELM and resting-state vmHRV as a function of several moderators, including mean age of and presence of psychopathology in the respective study sample. In the second study, resting-state and vmHRV recovery following stress exposure were identified as potential predictors of clinical improvement over the time course of two years in adolescent females with higher and lower dimensional manifestations of BPD. The third study revealed altered CVP of ANS activity in NSSI disorder compared to healthy controls, and in association with more severe ELM exposure, and critical confounders of the respective associations were identified. The present synopsis aims to integrate these findings into a psychophysiological framework of ER in development, and discuss methodological considerations, limitations, and potential future directions resulting from the studies that constitute the thesis at hand.