Psychological wellbeing in relation to morbidity and mortality risk: exploring associations and potential mechanisms
Okely, Judith Anna
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There is evidence of a prospective association between wellbeing and health outcomes including disease risk and longevity. The aim of this thesis was firstly to further explore whether wellbeing is a risk factor for specific chronic physical diseases, and secondly, to identify potential mediators and moderators of the association between wellbeing and disease risk or longevity. Chapter 1 provides an overview of research into associations between wellbeing and physical health. In addition, we outline theoretical models of how the experience of high wellbeing might impact physical health. In chapters 2 and 3, we build on research into wellbeing and chronic physical disease risk. In these chapters, we tested whether the association between wellbeing and disease risk was similar across different types of disease, and, whether different theoretical domains of wellbeing varied in their association with disease risk. We found particularly strong associations – that were not explained by demographic or health behaviour differences – between higher wellbeing and lower risk of arthritis, diabetes or chronic lung disease. In chapter 4, we further explore the association between wellbeing and arthritis risk using mediation analysis. Specifically, we tested whether this association was mediated by inflammatory biomarkers. We found that the biomarker C-reactive protein accounted for a small proportion of the association between wellbeing and a reduced risk of arthritis. The focus of the next two chapters was on potential moderators of the association between wellbeing and mortality risk. In chapter 5, we examined whether the association between higher wellbeing and lower mortality risk varied across individualist and collectivist cultures. We found a significant interaction between individualism and wellbeing such that the association between wellbeing and risk of mortality from cardiovascular disease was stronger in more individualistic countries. In chapter 6, we examined how positive affect (a subdomain of wellbeing), interacted with another psychosocial factor, namely subjective stress. Here, we tested Pressman and Cohen’s (2005) stress buffering hypothesis that positive affect may be most strongly related with health under stressful conditions. In support of this hypothesis, we found that the association between positive affect and all-cause mortality risk was stronger in people reporting higher stress. In the final chapter, we summarise our findings, discuss the limitations of our approach and make recommendations for future research.