To test whether epigenetic aging mediates associations between social connectedness and later cognitive function among U.S. older adults.
Methods
Using Health and Retirement Study data (N = 1,574; mean age = 68.5), we modeled 2014 social connectedness as a latent factor (participation, isolation, loneliness), assessed four DNA methylation clocks in 2016 (DNAmGrimAge, DunedinPoAm, DNAmPhenoAge, Zhang), and cognition in 2018. Survey-weighted regression-with-residuals mediation models adjusted for socio-demographics, smoking, obesity, self-rated health, heart disease, baseline cognition, and complex design.
Results
Lower social connectedness predicted poorer 2018 cognition (ATE ≈ −0.047 to −0.048 across models, p < .05). Only DNAmGrimAge showed evidence consistent with mediation (NIE = −0.008, SE = 0.004, p = .041; ≈16% mediated), whereas indirect effects via DunedinPoAm, PhenoAge, and Zhang were not supported (all p > .05).
Discussion
Findings provide limited, clock-specific support for epigenetic mediation, with preliminary evidence implicating DNAmGrimAge.
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