Associations between social and intellectual activities with cognitive trajectories in Chinese middle-aged and older adults: A nationally representative cohort study

Background: Associations between the frequency of social and intellectual activities and cognitive trajectories are understudied in Chinese middle-aged and older adults. We aimed to examine this association in a nationally representative longitudinal study. Methods: The China Health and Retirement Longitudinal Study (CHARLS) is a nationally representative sample of Chinese middle-aged and older participants. The frequency of social and intellectual activities was measured at baseline. Interview-based cognitive assessments of orientation and attention, episodic memory, and visuospatial skills and the calculation of combined global scores were assessed every 2 years from 2011 to 2016. Cognitive aging trajectories over time were analyzed using group-based trajectory modeling, and the associations of the trajectory memberships with social and intellectual activities were analyzed using multinomial logistic regression. Odds ratios (OR) and 95% confidence intervals (CI) were reported. Results: Among 8204 participants aged 50-75 years at baseline, trajectory analysis identified three longitudinal patterns of cognitive function based on the global cognitive scores: "persistently low trajectory"(n = 1550, 18.9%), "persistently moderate trajectory"(n = 3194, 38.9%), and "persistently high trajectory"(n = 3460, 42.2%). After adjustment for sociodemographic variables, lifestyles, geriatric symptoms, and health conditions, more frequent intellectual activities (OR 0.54, 95% CI 0.38-0.77) and social activities (OR 0.79, 95% CI 0.65-0.95) were both associated with a lower likelihood of being in the "persistently low trajectory"for global cognitive function. Conclusions: These findings suggested that more frequent social and intellectual activities were associated with more favorable cognitive aging trajectories.