Childhood socioeconomic status, cognitive reserve, and cognitive aging trajectories: a 10-year population-based cohort study

Childhood socioeconomic status (cSES) and cognitive reserve (CR) may shape late-life cognition, yet their distinct effects on cognitive level and age-related cognitive decline, and the mediating pathway through CR, remain unclear. Data were drawn from the Study on Ageing and Adult Health in China. cSES was derived from parental educational attainment and occupational complexity, while a proxy-based CR was operationalized from participants’ educational attainment, occupational complexity, and social engagement. Latent class mixed models identified cognitive trajectories, and Poisson regression assessed associations of cSES and CR with these trajectories. Linear mixed models examined associations of cSES and CR with cognitive level and decline across attained age. Mediation analyses evaluated indirect associations through CR. Among 13,357 participants aged ≥50 years, two cognitive decline trajectories were identified: high baseline level with gradual decline (25.3%) and low baseline level with rapid decline (74.7%). High cSES and high proxy-based CR were independently associated with the favorable trajectory, higher cognitive level, and slower cognitive decline across attained age. The proportions mediated through proxy-based CR were 29.6% for trajectories, 19.2% for cognitive level, and 57.8% for age-related cognitive decline. These findings suggest a double advantage/disadvantage pattern that may contribute to widening inequalities in cognitive aging.