Influence of lifespan cognitive reserve indicator on cognitive trajectories in different domains: role of brain pathologies

Abstract

AbstractBackgroundEvidence on the association of the cognitive reserve (CR) with the cognitive trajectories is limited. We examined the influence of lifespan CR indicator on domain‐specific cognitive trajectories taking brain pathologies into account.MethodWithin the Rush Memory and Aging Project, 1,697 dementia‐free participants (mean age: 79.6 years) were followed up to 21 years. Lifespan CR indicator encompassing education, early‐life, mid‐life, and late‐life cognitive activities, and late‐life social activities was ascertained at baseline and categorized by tertiles (lowest, middle, and highest). Global cognition, episodic memory, semantic memory, working memory, visuospatial ability, and perceptual speed were assessed annually with 19 tests battery, from which composite scores were derived. During the follow‐up, 648 died and underwent autopsies, and brain pathologies were assessed. Data were analyzed using linear mixed‐effects models.ResultAmong all participants, the score of CR indicator ranged from ‐8.00 to 5.74 (mean: 0.00±2.23). In multi‐adjusted mixed‐effects models, compared to the lowest CR, the highest CR was related to slower decline in global cognition (β=0.028, 95% confidence interval [CI]: 0.012 to 0.043), episodic memory (β=0.028, 95% CI: 0.010 to 0.047) and working memory (β=0.019, 0.005 to 0.033) during the follow‐up. Moreover, the association of the highest CR with cognitive function changes remained significant among participants with high Alzheimer’s disease pathology or gross infarcts.ConclusionHigh lifespan CR indicator is associated with preserved global cognitive function, episodic memory, and working memory over time, even in the presence of brain pathologies.