High lifelong cognitive reserve prolongs disability‐free survival: The role of cognitive function

INTRODUCTION: The association between cognitive reserve (CR) and survival with independence is unknown. We examined whether lifelong CR accumulation is associated with disability‐free survival and explored the extent to which cognitive function mediates this association. METHODS: Within the Rush Memory and Aging Project, 1633 dementia‐ and disability‐free participants were followed annually for up to 22 years. Lifelong CR including education, early‐/mid‐/late‐life cognitive activities, and late‐life social activity was assessed and tertiled. RESULTS: CR score was dose‐dependently associated with disability/death (hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.93–0.99). Compared to low CR, the HR (95% CI) of disability/death was 0.82 (0.70–0.95) for high CR. The median disability‐free survival time was prolonged by 0.99 (95% CI 0.28–1.71) years for participants with high CR. Cognitive function mediated 35.7% of the association between CR and disability‐free survival. DISCUSSION: High lifelong CR was associated with prolonged disability‐free survival. Cognitive function mediates about one‐third of this association. Our findings underscore the importance of CR for healthy aging.