The psychobiological response to acute stress and long-term stress resilience

Abstract

Resilience is the outcome of successful adaptation to stress and adversity. Individuals with high level of resilience are able to maintain good mental health even after exposure to stressful life events, and they are protected from chronic stress-induced psychological symptoms. In this thesis, resilience is considered as a dynamic adaptive process that should be explored using an integrative multi-systemic approach. In this context, I consider multiple interrelated biological, physiological and psychological processes relevant to stress responses and outcomes. Stress responses entail multiple biological and psychological mechanistic processes, but the interaction of the psychobiological processes in shaping resilience is still unclear. To fill in this research gap, I conducted three studies in this thesis to examine the interrelationship among different psychobiological responses and outcomes to stress, and long-term stress resilience.

Study 1 was a meta-analytic review on the psychobiological responses to acute stress, and their relationships with long-term stress outcome and resilience traits. The most important findings were that salivary cortisol and negative perceived emotions were the most salient psychobiological markers for acute stress response and recovery. In addition, limited evidence indicated that salivary cortisol responses to acute stress were associated with early-life trauma experience, and with resilience traits measured by questionnaires. Study 2 was an original investigation on the association among salivary cortisol responses to acute stress, traits related to positive emotion regulation, and long-term stress resilience. I adopted the operational definition of long-term stress resilience as the health outcomes following major life stress. Therefore, variables that modulate the relationship between an individual’s past major life stress experience, and her/his current psychological symptoms, were considered as resilience markers. Results indicated that both anticipatory cortisol response and positive affectivity traits negatively moderated the stress-symptom relationship. Specifically, the positive relationship between life stress and current symptoms was only observed at low, but not high, levels of cortisol response and trait positive affectivity, the latter consisting of trait positive affect and positive emotion regulation. Moreover, the moderating effect of cortisol response on the stress-symptom relationship was only observed at low but not high level of trait positive affectivity, signifying a moderated moderating effect. Study 3 took a further step to investigate if long-term stress resilience was modulated by variations in basal cortisol functioning as measured by cortisol awakening response, and cognitive attribution styles. Results showed that cortisol awakening responses negatively moderated the stress-symptom relationship, while negative cognitive style positively moderated the stress-symptom relationship.

The integrative results from the three studies revealed how biological and emotional processes of stress responses interact to shape resilience to major life stress. These results provided the first empirical evidence to unravel the intricate interplay between the psychobiological processes of stress response, and how these processes moderated the psychological health outcomes subsequent to the impact of major life stress. The identification of resilience markers has implications for pinpointing individuals with high psychobiological vulnerability to major life stress, as well as providing interventive targets for enhancing resilience and mental health outcomes to chronic stress.