Abstract 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.
Herd et al. (2026) studied this question.