Associations between life-course cognitive reserve and cognitive domains over 8 years in a large cohort of middle-aged and older adults: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

INTRODUCTION: Cognitive reserve (CR) arises from cognitively enriching experiences over time and may buffer against cognitive decline. However, the mechanisms underlying CR in low- and middle-income countries (LMICs) remain underexplored. This study investigated the latent structure of CR using socioeconomic and occupational indicators, and evaluated whether CR categories are associated with cognitive trajectories over 8 years. METHODS: In the ELSA-Brasil study, we derived a CR construct via principal component analysis from five indicators: education, occupational social class, occupational nature, technological stratum of work, and leisure-time physical activity. Memory, verbal fluency, and executive functioning were assessed at three waves; longitudinal trajectories were analyzed using mixed-models. RESULTS: Participants with higher CR exhibited significantly slower age-related cognitive decline across multiple domains, after controlling for demographic and health covariates. DISCUSSION: In a middle-income country with strong socioeconomic inequalities, early-life socioeconomic conditions were key determinants of CR development, contributing to disparities in late-life cognitive aging.