Physical exercise and depressive symptoms in older Chinese adults: roles of IADL functional status and social interaction

Background In the context of global population aging, examining how physical exercise relates to depressive symptoms in older adults and the possible pathways that may underlie this association is important for promoting mental health. This study investigated the association between physical exercise and depressive symptoms among older Chinese adults and explored whether IADL functional status and social interaction help to explain this association. Methods Using cross-sectional data from the 2018 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), we analyzed 7,299 respondents aged ≥ 65 years. We estimated adjusted associations between physical exercise and depressive symptoms using multivariable regression models with extensive covariate adjustment and several robustness checks, including alternative model specifications and propensity score matching. In an exploratory manner, potential pathways involving IADL functional status and social interaction were examined with regression-based analyses of cross-sectional associations and bias-corrected bootstrap confidence intervals, rather than with fully identified causal mediation models. Results Physical exercise was modestly but significantly associated with lower depressive symptom scores in older adults, and this association was generally robust across sensitivity analyses. IADL functional status and social interaction together appeared to account for a limited but non-trivial share of the overall association: the indirect pathway via IADL functional status was comparatively larger than that via social interaction, and we observed some evidence consistent with a small sequential pattern from IADL functional status to social interaction. The direct (unmediated) component of the association remained the largest. In sex-stratified analyses, the inverse association between exercise and depressive symptoms appeared stronger among men than among women, and the association was not statistically significant among older adults reporting financial hardship. Conclusion In this large observational sample of older Chinese adults, current participation in physical exercise was associated with lower levels of depressive symptoms, with patterns partly consistent with possible pathways involving IADL functional status and social interaction. Because all analyses are based on cross-sectional data and a crude measure of exercise, these results should be interpreted as correlational rather than causal. Even with these limitations, the findings suggest that promoting age-friendly opportunities for physical exercise may form one component of broader efforts to support late-life mental health in China.