Advancing the Study of Social Isolation, Loneliness, and Cognitive Functioning in Older Adults Through the Use of Integrative Data Analysis

PROJECT SUMMARY Impoverished social relationships are major contributors to morbidity and mortality, rivaling the effects of established risk factors such as cigarette smoking and obesity. Both social isolation (the lack of social contact) and loneliness (the perception of being alone) have been linked with cognitive morbidity and risk of Alzheimer's and related dementias (ADRD) in older adults, but the relative contribution of loneliness and social isolation to cognitive outcomes remain poorly understood. Similarly, the extent to which the discordance between social isolation and loneliness accumulates across the adult life span, from midlife to old age, and whether this relates to cognitive morbidity, decline, and dementia risk in older adults is unknown. Of particular interest is the extent to which older adults' vulnerability to isolation and loneliness is amplified amid physical distancing measures introduced in response to the COVID-19 pandemic and the long-terms impacts this may have on cognitive health. This proposal will investigate the hypothesis that changes in the degree of overlap or discordance between subjective feelings of loneliness and objective social network size (social asymmetry) contribute to cognitive function, decline, and dementia risk, and intensify older adults' cognitive vulnerability during COVID-19. To achieve the goals of the project, we will capitalize on existing large-scale longitudinal studies that have collected a broad array of psychosocial and cognitive factors, including repeated assessments of social isolation, loneliness, and established indicators of cognitive functioning (e.g., numeric and abstract reasoning, fluency, speed of processing and reaction time, working and episodic memory). The proposed project will use a coordinated integrative data analysis (IDA) approach to investigate whether changes in social asymmetry predict cognitive outcomes across eleven representative, prospective, longitudinal cohort studies of aging (BHPS/US, ELSA, HILDA, HRS, LISS, Octo-Twin, SATSA, SHARE, SHP, SOEP, and UCL COVID-19 Social Study) with a combined N of over 220,000). The central hypothesis of this proposal is that susceptibility to loneliness may be characterized by the discrepancy between objective and subjective aspects of social relationships which 1) is evident across middle and later adulthood; 2) contributes to cognitive decline in old age; and 3) exacerbates cognitive vulnerability in the context of the COVID-19 pandemic. The findings from this study will provide novel insights into the interplay between social isolation and loneliness over time, as well as how dynamic patterns of social asymmetry are linked to diverse cognitive outcomes in older adults. Better understanding of the role of social disparities in cognitive aging may lead to evidence-based strategies for addressing social isolation and loneliness in older adults, identification of modifiable social factors that may prevent or slow the progression of cognitive decline in old age, and novel approaches for understanding the impact of prolong social distancing on the health of older adults.