Emotion processing and dimensions of self-reported depression, anxiety and stress: A twin study of the specific and shared genetic and environmental contributors in males and females

Abstract

This thesis sought to understand the shared versus unique gene and environment contribution to self-reported dimensions of depression and anxiety using the Depression Anxiety and Stress Scale (DASS-42), together with behavioural and fMRI measures of facial emotion processing. In addition, it sought to understand the differentiation of the proportion of genetic and environmental contributors between males and females given known sex differences in depression and anxiety prevalence. The findings suggest that genetics have a moderate role in the aetiology of symptoms of depression and anxiety, and a variable role, with heritability ranging from nil to moderate, for behavioural and fMRI measures of emotion processing. Specific associations were evident between depression and anxiety symptoms and measures of emotion processing, with effects predominantly specific to certain emotional expressions and/or regions in the brain. There was some variation in whether this shared variance was mostly attributable to common genetic or environmental factors. The proportion of genetic and environmental contributors for specific measures and the patterns of association also varied in males and females. The findings of this study are discussed in light of general study limitations and clinical implications for the examination of dimensions of symptoms of depression and anxiety.