Cognitive Activity From Early to Late Life and the Risk of AD Dementia: A Life Course Study

Participation in late-life cognitive activities has been associated with a slower rate of cognitive decline and reduced risk of dementia; however, whether this association is independent of earlier experiences is unclear. We examined the association of cognitive activities during early life, midlife, and late life with the risk of Alzheimer's disease (AD) dementia.

This study used data from the Chicago Health and Aging Project, a longitudinal population-based study from 1993 to 2012. Cognitive activity in early life, i.e., during childhood, was measured by the frequency of activities such as reading, storytelling, and playing games. Cognitive activity in midlife was estimated based on the participants' occupational cognitive activity and complexity. Cognitive activity in late life was assessed by the frequency of participation in reading, watching TV, listening to the radio, visiting museums, and playing chess or checkers. Cognitive activity in early, midlife, and late life was standardized to the population standard deviation (SD) and was modeled continuously (i.e., per 1-SD increase) and categorically (i.e., tertiles). Clinical diagnosis of AD dementia was based on the established criteria by NINCDS-ADRDA. Logistics regression models were used to estimate the odds ratio (OR) and 95% confidence interval (CI) of cognitive activities with AD dementia.

Of the 1950 individuals included in the analysis, 63% were female, and 54% were Black adults. The average age of study participants was 73. Three hundred ninety-one (20.1%) individuals developed AD dementia during the study period. Cognitive activity in midlife and late life was independently associated with a lower risk of AD dementia, while early-life cognitive activity was not. The OR (95%CI) for a 1-SD increase in the cognitive activity score in early, midlife, and late life were 0.91 (0.71, 1.18), 0.66 (0.51, 0.87), and 0.50 (0.38, 0.65), respectively. Comparing people in the high cognitive activity group (3rd tertile) versus those in the lower group (1st tertile) provided similar associations.

Cognitive activity in midlife and late life was associated with a lower risk of AD dementia. In addition, this study supports the independent role of late-life cognitive activity on the risk of AD dementia.