A longitudinal study of socioeconomic status and cognitive function in middle-aged and older adults in China: random intercept cross-lagged panel analysis

This study aimed to examine the reciprocal associations between socioeconomic status (SES) and cognitive function by disentangling between-person and within-person effects, and further examined potential heterogeneity across six specific subgroups: age, gender, residence, ever smoking, ever drinking, night sleep duration, and depressive symptoms. The data analyzed were drawn from the China Health and Retirement Longitudinal Study (CHARLS) during 2011-2018. Cognitive function was assessed by intelligence and episodic memory. SES was operationalized using annual per-capita household expenditure, occupation, education level, and health insurance. Adjusted random intercept cross-lagged panel models (RI-CLPMs) and multiple group RI-CLPMs were used to determine the reciprocal relationship between cognitive function and SES. Among 9,322 participants, at the between-person level, middle-aged and older adults showed positive association between SES and cognitive function over an eight-year period after adjusting covariates (β = 0.545, P < 0.001). At the within-person level, SES and cognitive function exhibited reciprocal positive cross-lagged effects across wave 2 to 4 (β = 0.032-0.063, P < 0.050). Using multi-group RI-CLPMs, we identified differences in the longitudinal effect of SES on cognitive function, particularly when comparing groups based on the residence and depressive symptoms (P < 0.050). An increase in individual socioeconomic status was a positive predictor of cognitive function. Likewise, improvements in cognitive function were found to positively predict short-term gains in socioeconomic status. These findings suggest that tailored interventions should be developed to prevent cognitive aging, taking into account the heterogeneity of different population.