Causal Inference
Social Disconnectedness and Cognitive Functioning: An Application of a Novel Causal Inference Approach for Health Disparity Research Xi Wang* Xi Wang Toshiaki Komura Koichiro Shiba
Background: Social disconnectedness can be a threat to disparities in the cognitive functioning of older adults, yet prior research has examined its impacts on the population average outcome rather than its disparities.
Methods: We analyzed the longitudinal data of adults aged ³ 50 from the Health and Retirement Study (HRS; n = 11,322) and the English Longitudinal Survey of Aging (ELSA; n = 5,179). We assessed binary exposures of social isolation and loneliness at baseline. Cognitive functioning was measured four years after the baseline. We assessed disparities in cognitive functioning by income, wealth, education, and race. Controlling for 35 pre-baseline characteristics, we estimated the heterogeneous effects of disconnectedness on cognitive function using a causal forest algorithm. We simulated changes in the class-based and racial disparities in cognitive function under various interventional scenarios changing the exposure distributions.
Results: We observed existing disparities in both the exposure and the outcome. We found the population average association between social isolation and lower cognitive functioning in HRS (estimated ATE = -0.23; 95% CI: -0.35, -0.11) and ELSA (estimated ATE = -0.35; 95% CI: -0.54, -0.16). In HRS, we also found evidence of effect heterogeneity such that the association between social isolation and lower cognitive functioning was stronger among those with lower educational attainment and Black race but higher income and wealth. We found no effect of loneliness on cognitive functioning. Disparities in cognitive functioning were simulated to decrease under all hypothetical interventions reducing the prevalence of social isolation, particularly ones that addressed disproportionate distributions of the exposure itself.
Conclusion: Public health interventions reducing the population prevalence of social isolation and its disparities have the potential to narrow health disparities in cognitive functioning.
