Although previous studies have shown that intellectually engaging activities, which contribute to cognitive reserve, protect against cognitive impairment and dementia, little is known about the role that cognitive reserve plays in normal cognitive aging during the last decades of life. The aim of the current study is to examine whether substantively complex work in midlife, as a proxy for cognitive reserve, is associated with levels and rates of change in later-life cognition among cognitively normal individuals who did not develop dementia at any point of longitudinal assessments. Participants were 1,118 members of the Einstein Aging Study (mean age at baseline=79.2, SD=5.4; mean follow-ups=2.8 years; mean retirement age=64.9). Midlife occupation information of each participant was collected retrospectively at baseline and was linked with factor scores for substantive complexity of work derived from the US Dictionary of Occupational Titles (DOT), published by the US Department of Labor. Cognitive function was assessed annually using nine neuropsychological tests that represent memory, speed, and language. Analyses from mixed models showed that higher complexity of work was associated with higher initial levels of cognitive scores (ps<.05). Interestingly, higher complexity of work was associated with steeper decrease in speed (Digit Symbol-Coding subtest, p<.01; Trail Making Test Part A, p<.01) and memory (Logical Memory, p<.05) scores decades after retirement. This seemingly paradoxical result is in line with the cognitive reserve hypothesis (Stern, 2002) such that protective factors for cognitive aging may be associated with delayed onset but more rapid cognitive decline in the later stages of life.
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