Moderated Chain Mediation of Depression and Social Participation Between Stroke and Mortality by Socioeconomic Status

Background: Stroke significantly increases the risk of depression and reduced social participation, particularly among middle-aged and older adults. Socioeconomic status (SES) may further shape these pathways. This study examined the mediating roles of depression and social participation, and the moderating role of SES, in the relationship between stroke and 10-year all-cause mortality in Chinese adults, while also exploring longitudinal patterns over time. Methods: We analyzed data from 7,101 participants in the China Health and Retirement Longitudinal Study (CHARLS) across five waves (2011-2020). Depression was assessed via the CES-D scale, and social participation was measured based on activity frequency scores. SES was constructed from education, occupation, expenditure, and insurance. Moderated chain mediation models and generalized linear mixed models were used to evaluate pathways and temporal trends. Results: Stroke was significantly associated with higher all-cause mortality. Depression partially mediated this association (β = 0.059, 95% CI [0.020, 0.023]). Although social participation alone was not a significant mediator, a sequential pathway involving depression and social participation was confirmed (β = 0.006, 95% CI [0.001, 0.012]). SES moderated both the stroke-depression and depression-social participation pathways. Notably, social participation demonstrated a protective role against post-stroke mortality when embedded within depression-related pathways--especially among low-SES individuals. Longitudinal analyses showed that the effects of stroke and depression on mortality weakened over time, while high levels of social participation consistently offered protective benefits. Conclusions: Depression and social participation mediate the stroke-mortality relationship, and SES plays a critical moderating role. These findings suggest that strengthening social engagement may serve as an effective strategy to mitigate depression-related mortality among stroke survivors, particularly in low-SES populations. Tailored, SES-sensitive interventions are essential to improving survival outcomes.