The Mediating Role of Cognitive Function in the Relationship Between Physical Performance and Depressive Symptoms Among Older Adults in China: A Prospective Longitudinal Study.

Background: Depressive symptoms in the elderly have become a growing public health problem as the population ages rapidly and the imbalance between supply and demand of mental health resources exists. This study aims to explore the predictive power of physical performance on depressive symptoms in Chinese older adults, examine the mediating role of cognitive function, and analyze its variations across genders. Methods: In this study, we included 3779 older adults aged 60 years and above who participated in the 2015 China Health and Retirement Longitudinal Study and completed follow-up in 2018. We employed binary logistic regression and three-knotted restricted cubic spline regression to examine the association between physical performance and depressive symptoms, assessed the mediating effect of cognitive function using the SPSS PROCESS macro, and analyzed the data separately in male and female subgroups. Results: The development of depressive symptoms during follow-up (n = 982) was preceded by significantly lower physical performance scores at baseline. After adjusting for confounding factors, the presence of the lowest baseline short physical performance battery (SPPB) scores was independently associated with an increased risk of incident depressive symptoms (OR, 1.972; 95% CI: 0.91-4.26), similar to the trend of restricted plots. Meanwhile, cognitive function is an intermediate variable between physical performance and depressive symptoms, and the mediating effect of men is stronger, at 14.92%. Conclusion: This study confirms that poor physical performance is independently associated with depressive symptoms in Chinese older adults at the 3-year follow-up and further reveals that cognitive function serves as a mediator in this association with gender-specific differences. These findings provide an important theoretical basis and potential clinical value for implementing targeted cognitive interventions in populations with declining physical function to alleviate depressive symptoms.