Effects of Cognitive Reserve on Cognition in Individuals With Central Nervous System Disease.

Cognitive reserve (CR) has been proposed to account for functional outcome differences in brain pathology and its clinical manifestations. The purpose of our paper is to systematically review the effects of CR on cognitive outcomes in individuals with neurodegenerative and structural CNS diseases. We performed a systematic search of PubMed, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and PsychInfo using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Seventeen studies met the predetermined inclusion criteria and were selected for review. Education level was the most commonly used measure for CR, and various neuropsychological tests were used to measure cognitive outcomes. Regardless of the CNS disease of the individuals, almost all of the studies reported a positive association between CR and cognitive outcomes when they were evaluated cross-sectionally. However, when evaluated longitudinally, CR had either no effect on, or a negative association with, cognitive outcomes. Based on studies across a broad spectrum of CNS diseases, our findings suggest that CR may serve as a predictor of cognitive outcomes in individuals with CNS diseases. However, studies to date are limited by a lack of imaging analyses and standardized assessment strategies. The ability to use a standardized measure to assess the longitudinal effects of CR may allow for the development of more targeted treatment methods, resulting in improved disease outcomes for individuals.