Abstract
BACKGROUND: China is experiencing rapid population aging and increasing dementia cases. Although existing evidence suggests a link between social participation (SP) and cognitive function (CF) in older adults, few studies have explored their long-term patterns and interplay across urban-rural groups. METHODS: We utilized five waves (2011, 2013, 2015, 2018 and 2020) of multivariate longitudinal data from the China Health and Retirement Longitudinal Study, categorizing participants into urban and rural groups by residence. A group-based dual trajectory model was employed to examine the heterogeneous trajectories and bidirectional association of social participation and cognitive function among 4,133 participants. Binary and multinomial logistic regression analyses were used to explore the predictors of different trajectories. A multigroup cross-lagged panel model was applied to explore the bidirectional associations between social participation and cognitive function. RESULTS: Among the rural participants, three social participation trajectories were identified: "No SP" (45.2%), "Low SP" (47.5%) and "Moderate SP" (7.3%), and the urban areas included two: "No SP" (62.3%) and "Low SP" (37.7%). There were three patterns of cognitive function in rural areas: "Low-Decline CF" (28.4%), "Moderate-Decline CF" (39.0%) and "High-Decline CF" (32.6%), while urban areas had two: "Low-Decline CF" (49.8%) and "High-Decline CF" (50.2%). Sleep duration was a common risk factor for SP and CF in rural participants (p < 0.05). Individuals with higher levels of social participation were also more likely to exhibit better cognitive function (rural: 79.08%; urban: 65.89%). The cross-lagged analysis showed that cognitive function at the previous wave had a significant positive effect on subsequent social participation (p < 0.05). CONCLUSIONS: The long-term developmental trajectories of social participation and cognitive function are synchronized, primarily driven by the positive effect of cognitive function on social participation. Rural older adults exhibited greater heterogeneity in their trajectories and more complex predictors than their urban counterparts. Interventions targeted at the urban‒rural context are recommended to reduce cognitive decline and promote health equity.