Social Vulnerability and Health in Older Adults
Andrew, Melissa Kathryn
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Vulnerability to adverse health outcomes can be intrinsic (e.g. illnesses, disability, frailty, genetics) or extrinsic (e.g. physical and social environments). The contribution of social factors to extrinsic vulnerability in older adults is the subject of this thesis. Social vulnerability is the degree to which a person’s overall social situation leaves them susceptible to further insults, either health-related or social. This thesis begins with an exploration of how various social factors are associated with health and can be considered to contribute to a holistic concept of social vulnerability. Using a social ecology perspective, seven domains of social vulnerability (engagement, contextual socio-economic status, social support, living situation, self-esteem, mastery, and relations with others) are defined. A social vulnerability index is then developed, in which social factors from all of these domains are combined into a single index, allowing the complexity of social circumstances experienced by older people to be embraced. Social vulnerability, defined using this index, is then studied in relation to health, and is found to be associated with frailty, mortality and cognitive decline. The important impact of social vulnerability on the survival of the fittest older adults (those who are not at all frail) is studied as a special case. How social vulnerability changes over time is then examined using a transitions model based on a parametric Markov chain, with the finding that older people tend to accumulate social deficits over time, but that, importantly, this relentless accumulation of social problems is not a universal experience. The thesis then turns to consideration of frontal lobe cognitive function as a possible mechanism for the association between social vulnerability and health, given the importance of the frontal lobes to social interaction in humans. It finds that the most socially vulnerable people have impaired performance on tests of frontal lobe cognition, but that performance on non-frontal tasks is not similarly associated. The findings presented in this thesis support the importance of social factors for health of older people, and suggest that the social vulnerability index shows potential as a measure which embraces the complexity of older adults’ social circumstances while reducing dimensionality.