Social relationships and progression of frailty : exploring the reciprocal association of social ties and physical vulnerability in later life

Frailty is described as a state of heightened vulnerability and functional impairment due to the cumulative declines across multiple physiological systems. When faced with stressor events, older adults with frailty are in higher risk of adverse health outcomes. While the prevalence of frailty generally increases with age, there are considerable heterogeneity in onset and progression of frailty among older population. Growing attention is given to identifying the psychosocial factors related to the development of frailty. Social relationships often serve as a vital context of health, where older adults experience multidimensional and dynamic exchange with close others as they age. In this dissertation, two studies are conducted to investigate complex and reciprocal nature of social relationships and frailty progression in older adulthood. The data are from the six waves (2006-2016) of the Health and Retirement Study (HRS), a nationally representative study of older adults in U.S. aged 50 and older. The first study utilized the convoy model of social relations to provide comprehensive investigation of how different aspects of social relations are associated with frailty progression over a decade. There were three distinctive subpopulations following a different frailty progression trajectory. When social network and relational quality with spouse, children, family, and friends were examined, higher frequency of contact with friends were associated with lesser frailty. Negative relationship quality with social ties were detrimental to frailty progression, such that strain with spouse and kin (children and extended family) had an additive effect on belonging to high frailty or steep increase frailty trajectory groups. The perceived loneliness partially explained the negative effect of spousal strain, but the negative effect of large family size and strain with kin were independent from loneliness. The second study explored the health contexts of older couple's marital quality, specifically focusing on the presence of frailty and depression within- and across-person in the marital relationship. Using three waves of dyadic data from HRS, I found that one's own and partner's higher frailty and higher depression all had independent associations with one's higher marital strain. For one's marital support, one's own higher frailty, higher depression, and partner's higher depression had negative effects. There was an across-person interaction effect of frailty, such that one's marital quality was affected by their partner's higher level of frailty only when their own health was good. Having a husband with higher frailty was associated with higher marital strain for wives. Most effects were stable over time. Overall, the findings illustrate the significance of social relationship context as a predictor for different trajectory of frailty progression. The size, frequency of contact, positive, and negative quality were linked to frailty differentially by relationship type, underscoring the benefits of comprehensive examination of social experiences. Further, the level of frailty and depression were linked to perceived marital quality of both members of the couple, especially in damaging manner when healthier spouse is faced with partner's health problems. Taken together, my dissertation demonstrated the importance of studying linked lives in context of health conditions prevalent in older adulthood. The findings can be useful to practitioners and policy makers in understanding the intricate link between social relations and frailty as well as in identifying modifiable factors for frailty prevention.