Socioeconomic status and cognitive function in older adults: the mediating roles of social activity and loneliness in three aging cohorts.
BACKGROUND Cognitive impairment among older adults poses a substantial and growing public health burden. Despite established links between SES and cognition, the psychosocial pathways and their variation across national contexts remain unclear. This study examines the relationship between SES and cognitive function in middle-aged and older adults, and explores the mediating roles of social activity and loneliness in this association. METHODS Using data from the China Health and Retirement Longitudinal Study (CHARLS), the Health and Retirement Study (HRS) in the United States and the English Longitudinal Study of Ageing (ELSA), we analyzed participants aged ≥ 50. SES was derived from latent class analysis of family income, educational level, and employment status. Cognitive function was assessed through standardized tests. Linear mixed models evaluated SES-cognition associations, and mediation analyses explored potential associative pathways. RESULTS Higher SES was significantly associated with better cognitive function in all cohort studies, with the strength of the association varying cross-nationally: strongest in CHARLS (β = 0.21, 95% CI: 0.16-0.26), intermediate in HRS (β = 0.14, 0.11-0.17), and weakest in ELSA (β = 0.031, 0.003-0.058). Social activities mediated 7.28% to 12.08%, and loneliness mediated 1.89% to 18.33% of these associations. The relationships remained consistent across the subgroups. CONCLUSION Socioeconomic status demonstrated a robust, graded association with cognitive function in older adults, with this relationship partially mediated by social activity involvement and loneliness. The cross-national gradient in effect sizes suggests that macro-level structural and policy contexts may substantially moderate this relationship. These findings highlight the need for integrated interventions addressing both psychosocial mediators and structural determinants to reduce cognitive health disparities.