Education and Age-related Decline in Cognitive Performance: Systematic Review and Meta-analysis of Longitudinal Cohort Studies
Central theories of cognitive aging propose that education is an important protective factor for decline in cognitive performance in older age. We conducted a systematic review and meta-analysis of reported estimates of an association between educational attainment and change in performance in six cognitive domains (episodic memory, processing speed, verbal fluency, crystallized intelligence, fluid intelligence, and global ability) in the general population of older individuals. The systematic search (28th of September, 2018) identified 83 eligible articles. The episodic memory domain had the highest number of estimates (37 estimates from 17 articles, n=109,281) included in the meta-analysis. The fewest estimates (5 estimates from 5 articles, n=5,263) were included for fluid intelligence. Pooled mean estimates from an inverse-variance weighted random effects analysis were not statistically significant and indicated that any association between education and change in cognitive performance is likely to be of a negligible magnitude. Sensitivity analyses did not substantially alter these results. However, heterogeneity was substantial, and remained largely unexplained by mean age, mean educational attainment, maximum follow-up period, and publication year. Overall education is an important factor in aging due to its robust association with level of performance. However, we conclude that the current base of empirical evidence is not revealing a consistent and substantial association between educational attainment and changes in cognitive performance in the general population. Theories of cognitive aging must be updated to incorporate this pattern of findings.