Early‐life influences on the risk for later‐life Alzheimer's and non‐Alzheimer's dementia: A nearly full life course prospective cohort study

BACKGROUND: Dementia prevention research has largely used educational attainment as a proxy for early-life. Given the known influence of early-life exposures on brain development, more attention to early-life exposures is warranted. METHODS: We employ the Wisconsin Longitudinal Study, a nearly full life course cohort study, to examine the influence of prospectively measured early-life risk factors for dementia in later life. RESULTS: We find that early-life risk factors that precede high school completion, rather than early adulthood post-secondary schooling, exert influence on later-life dementia. Household parental resources influence non-Alzheimer's disease (AD), but not AD, dementia risk. In contrast, markers for adolescent cognitive reserve (cognitive and academic performance measures) influence AD dementia risk, in part, by modifying genetic risk. DISCUSSION: Using education as a proxy for early-life exposures conceals specific mechanisms that influence distinct dementia etiologies and are separately intervenable. Education's influence may be confined to the early-life and adolescent period, where brain development is especially malleable. HIGHLIGHTS: Educational attainment is commonly used as a proxy for early-life risk factors for dementia. Given known early-life influences on brain development, more attention to the period is warranted. Early-life parental income influences non-AD dementia risk. Early-life cognition and academic performance influence AD dementia risk. Using educational attainment as a proxy for early-life exposures conceals separate intervenable risk factors.