Stress in Healthy Young Women: Psychophysiological Stress Reactivity, Adverse Childhood Experiences and Chronotype

The main objective of the present dissertation was to contribute to the knowledge about the impact of stress on healthy young women. The first two studies aimed at gaining further knowledge about the psychophysiological consequences of stress experienced in childhood and adolescence on stress reactivity in early adulthood. Adverse childhood experiences (ACEs), as one form of chronic or prolonged stress exposure, can alter brain development, leading to mental and physical illness and alterations of stress system in adulthood. In the first study we wanted to replicate findings of blunted endocrine and cardiovascular stress reactivity in association with ACEs in a sample of healthy young women. Additionally, we investigated the association of age of occurrence and duration of adverse events with cortisol and heart rate reactivity. We could show that number of ACEs was associated with blunted cortisol and heart rate (HR) response to stress in a dose-response relationship. Duration of ACEs was associated only with blunted cortisol response and age of occurrence did not contribute further to the blunted stress response. In the second study we wanted to investigate whether blunted cardiovascular stress response is due to less sympathetic activity (indexed by systolic blood pressure, SBP) or less parasympathetic withdrawal (indexed by respiratory sinus arrythmia, RSA). A mediation model showed that the effect of ACEs on HR was mediated by SBP but not RSA reactivity which indicates a downregulation in sympathetic activity. Future research will need to clarify whether these findings indicate risk or resilience. The aim of the third study was to shed more light on the association of chronotype and social jetlag with unhealthy habits and health related parameters. We could replicate the association among late chronotype, social jetlag and higher alcohol consumption. Furthermore, our results suggest a relationship between ACEs and chronotype. Although it can be hypothesized that it is rather ACEs that have an impact on chronotype, further research is needed to explore this relationship more. In conclusion, results of the present dissertation corroborate the knowledge about the altering impact of different stressors on behavior and psychophysiological functioning even in a sample of healthy young women. In the same time, results also show that our sample was not impacted by these stressors at all levels which may imply the presence of protective factors or the adaptive nature of alterations of psychophysiological mechanisms.