THE ASSOCIATIONS BETWEEN PSYCHOLOGICAL WELL-BEING, PHYSICAL FUNCTIONING, AND IMMUNOSENESCENCE IN AGING

Abstract

With the global population aging at an unprecedented rate, there is mounting concern regarding the increasing burden of chronic diseases and physical disability among older adults. Identifying factors that promote healthy aging is a critical public health priority. This dissertation investigates the associations between psychological well-being and various aspects of healthy aging, including physical functioning, progressive parkinsonism, and immune aging. In Study 1, I examined whether higher levels of optimism are associated with sustained levels of performance-based measures of physical function over 6 years of follow-up. Using a longitudinal cohort of women from the Women’s Health Initiate, I assessed physical function using three different performance-based measures (i.e., grip strength, walking speed, and chair stands). In Study 2, I evaluated whether higher levels of purpose in life are associated with lower levels of parkinsonian signs, lower increase of parkinsonian signs over follow-up, and lower incidence of parkinsonism over an average of 7 years follow-up. I used longitudinal data from the Memory and Aging Project (MAP) and Minority Aging Research Study (MARS) to assess these associations in White and Black women and men. In Study 3, I investigated whether higher levels of optimism and purpose in life are associated with indicators of the immune function that are indicative of decelerated immune aging. With data from the Health and Retirement Study, I assessed the cross-sectional association for T cell subsets and cytomegalovirus IgG antibodies. Across the three studies, I considered a range of potential confounders including sociodemographic factors, baseline health conditions, and depressive symptoms. In particular, because depression is an important potential confounder, I assessed associations between psychological well-being and the respective health outcomes independent of depression to investigate if the benefits of psychological well-being may be seen beyond the absence of depression. Across the three studies, I found that having higher levels of psychological well-being were associated with maintaining higher levels of physical function (i.e., assessed by performance-based measures of physical functioning and parkinsonian signs) over time among older adults, and that immunosenescence may be one mechanism underlying the link between some of these facets of psychological well-being and healthy aging. These findings offer novel insights into the role of psychological well-being across various aspects of healthy aging, encompassing both mechanistic and outcome-oriented processes. Future research should explore whether interventions targeting psychological well-being result in healthy aging.