The potential mediating role of social frailty in the associations of cognitive function, sleep duration, and life satisfaction with depressive symptoms in older adults: a cross-sectional study using CHARLS data

To examine the direct and indirect associations of cognitive function, life satisfaction, and sleep duration with depressive symptoms, with social frailty as a potential mediator, among older adults. Cross-sectional data from Wave 5 (2020) of the China Health and Retirement Longitudinal Study (CHARLS; N = 4,491; aged ≥ 60 years) were analysed. Depression was measured using the CESD-10, cognitive function using a composite score (orientation, memory, and executive function), and social frailty as a sum of loneliness and social isolation scores. Hierarchical regression and structural equation modelling were conducted. The mean depression score was 16.97 (SD = 5.78). In hierarchical regression showed that life satisfaction (β = −0.265), cognitive function (β = −0.257), sleep duration (β = −0.174), health status (β = −0.156), social frailty (β = 0.113), and self-rated memory (β = −0.073) were significantly associated with depression symptoms, collectively accounting for 28.7% of variance. Path analysis further showed statistically significant indirect associations through social frailty linking life satisfaction, cognitive function, and sleep duration to depressive symptoms. These findings suggest a complex interplay among life satisfaction, social frailty, sleep duration, cognitive function, and depressive symptoms in older adults. Social frailty may serve as a potential intermediary pathway linking these factors to depression. As the cross-sectional design precludes causal inference, longitudinal studies are needed to confirm directionality and evaluate whether interventions targeting social frailty can reduce depressive symptoms in ageing populations.