Moderate-to-vigorous physical activity and cognition among older adults in China: Mediation by depressive symptoms and moderation by age

Objectives To examine the association between moderate-to-vigorous physical activity (MVPA) and global cognitive function among older Chinese adults, and to assess the mediating role of depressive symptoms and moderating role of age in this association. Study design Cross-sectional, survey-weighted analysis of CHARLS 2020. Methods We analysed data from 5318 community-dwelling adults aged ≥60 years participating in the 2020 wave of the China Health and Retirement Longitudinal Study (CHARLS). MVPA was derived from the International Physical Activity Questionnaire–Short Form, and global cognition was assessed using education-adjusted z-scores constructed from episodic memory, figure drawing, and mental status items. Depressive symptoms were measured with the 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10). Survey-weighted linear regression models estimated associations between MVPA and cognition, progressively adjusting for sociodemographic, health, and behavioral covariates. Bias-corrected bootstrapped mediation analyses quantified the indirect association via depressive symptoms, and interaction terms with age tested moderation. All analyses incorporated survey weights, clustering, and stratification. Results Weighted mean age was 69.8 years, and 50.1% of participants were women; 32.6% met education-adjusted criteria for cognitive impairment. Higher MVPA was positively associated with better cognitive performance in models adjusting for sociodemographic, health, and behavioral factors (standardized β = 0.38, 95% CI 0.34–0.42), with the direct association attenuating but remaining significant after further adjustment for depressive symptoms (β = 0.30, 95% CI 0.26–0.34). Depressive symptoms partially mediated the MVPA–cognition association (indirect effect = 0.08, 95% CI 0.06–0.10), accounting for 21.1% of the total association. Age strengthened the positive MVPA–cognition association (interaction β = 0.025, 95% CI 0.015–0.035), with conditional slopes ranging from β = 0.25 at ∼63 years to β = 0.45 at ∼77 years. Conclusions Among community-dwelling older Chinese adults, higher MVPA was associated with better global cognitive function, with a meaningful portion of this association statistically attributed to lower depressive symptom burden and stronger effects observed at older ages. Although the cross-sectional design precludes causal inference, these findings support age-attuned MVPA promotion combined with routine mood assessment and support as a pragmatic strategy to help preserve late-life cognitive health