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).

A latent cognitive reserve construct was derived from five socioeconomic and occupational indicators using principal component analysis.

• The five indicators used were: education, occupational social class, occupational nature, technological stratum of work, and leisure-time physical activity.
• The study used the ELSA-Brasil cohort of middle-aged and older adults.
• Principal component analysis was used to derive the CR construct from these indicators.

Higher cognitive reserve was associated with significantly slower age-related cognitive decline across multiple cognitive domains over 8 years.

• Cognitive domains assessed included memory, verbal fluency, and executive functioning.
• Assessments were conducted at three waves over an 8-year follow-up period.
• Longitudinal trajectories were analyzed using mixed-models.
• Associations were found after controlling for demographic and health covariates.

Early-life socioeconomic conditions were key determinants of cognitive reserve development in this middle-income country sample.

• The study was conducted in Brazil, a low- and middle-income country (LMIC) characterized by strong socioeconomic inequalities.
• Early-life socioeconomic conditions contributed to disparities in late-life cognitive aging.
• The findings highlight that mechanisms underlying CR in LMICs involve socioeconomic pathways.

The mechanisms underlying cognitive reserve in low- and middle-income countries remain underexplored prior to this study.

• The study specifically addressed a gap in the literature regarding CR in LMICs.
• Most prior CR research has been conducted in high-income country settings.
• The ELSA-Brasil study provided a large cohort context to examine these mechanisms in a LMIC setting.

Higher cognitive reserve categories were associated with better cognitive trajectories across memory, verbal fluency, and executive functioning domains.

• Participants were categorized into CR categories derived from the principal component analysis.
• The protective association of higher CR was observed across all three cognitive domains assessed.
• Results were obtained using mixed-effects models accounting for repeated measures over the 8-year study period.