LIFE COURSE CONTEXT OF DISPARITIES IN DISABILITY

As the US population ages, scientists and policy makers are giving renewed attention to not just increasing the quantity of years lived but improving the quality of those years. Disability, defined as difficulty in performing basic, necessary, socially defined tasks such as bathing and eating, represents a threat to quality of life. Disability has been acknowledged as a major public health issue among policy makers, practitioners, and multidisciplinary researchers for older adults, yet few have investigated the lifetime predictors of this condition. The purpose of this dissertation is to (1) identify how exposure to stressful events across the life course influences disability, (2) examine the role that social relationships play in disability onset in later life, and (3) investigate the appraisal of stress rather than just the discrete occurrence of an event to understand how this subjective experience alters disability status in later life. This dissertation aims to understand how these relationships vary among demographic groups, with two chapters identifying racial, ethnic, and nativity disparities, and one explaining the moderating effect of gender. Drawing from life course theories including the stress process and cumulative inequality, this dissertation uses longitudinal data from the Health and Retirement Study (HRS) to examine the effect of lifetime stress exposure, adult social relationships, and chronic stress appraisal on the occurrence and onset of disability among adults 50 years and older. This dissertation is composed of an introductory chapter, three empirical chapters, and a concluding chapter.
The first empirical study investigates disparities in stress and disability and further examines how the relationship between stress exposure (both cumulatively and domain-specific) and disability differs by race, ethnicity, and nativity. The second empirical chapter examines the gendered relationship between patterns of social relationship quality in adulthood (identified by high quality, adverse, indifferent, or ambivalent) and the onset of disability in later life. The third empirical chapter builds on the conceptual design of the first chapter, but instead examines chronic stress exposure and chronic stress appraisal and how each has a unique influence on later-life disability for White, Black, US-born Hispanic, and foreign-born Hispanic adults. Overall, findings reveal that higher levels of stress exposure, more detrimental patterns of relationship quality, and appraising stress as upsetting are associated with an earlier onset of disability in later life among adults in the United States. Although empirical chapter 2 did not find any racial, ethnic, and nativity differences among social relationships and disability, negative relationship patterns (i.e., 13 adverse and ambivalent) are associated with disability at a younger age for all older adults. In addition, men who report adverse or indifferent relationships have higher odds of disability than men in high quality relationships. The two chapters examining different conceptualizations of stress exposure and disability find racial, ethnic, and nativity differences. Compared to White adults, cumulative stress burden, particularly childhood traumatic events, are especially harmful for US-born Hispanic adults. Moreover, appraising chronic stressors as more upsetting has a detrimental influence on later-life disability for Black adults, but a protective effect for foreignborn Hispanic adults.
This dissertation highlights several lifetime antecedents of disability and identifies that it is important to account for demographic factors when addressing interventions to reduce the overall occurrence of disability. Disability is more prevalent among older adults and represents a threat to quality of life. Interventions aimed at reducing exposure to stressful experiences and improving quality of relationships may alleviate some of the noxious effects that disability has on optimal aging.