To determine the association between blood pressure during midlife (40–64 years) to late life (≥65 years) and risk of incident dementia.

This study included 1,440 (758 women, mean age 69 ± 6 years) Framingham Offspring participants who were free of dementia and attended 5 consecutive examinations at 4-year intervals starting at midlife (1983–1987, mean age 55 years) until late life (1998–2001, mean 69 years) and subsequently were followed up for incident dementia (mean 8 years). We determined the effect of midlife hypertension (≥140/90 mm Hg), late life hypertension, lower late life blood pressure (<100/70 mm Hg), persistence of hypertension during mid- to late life, and steep decline in blood pressure from mid- to late life over an 18-year exposure period.

During the follow-up period, 107 participants (71 women) developed dementia. Using multivariable Cox proportional hazards models, we found that midlife systolic hypertension (hazard ratio [HR] 1.57, 95% confidence interval [CI] 1.05–2.35) and persistence of systolic hypertension into late life (HR 1.96, 95% CI 1.25–3.09) were associated with an elevated risk of incident dementia. However, in individuals with low to normal blood pressure (≤140/90 mm Hg) at midlife, a steep decline in systolic blood pressure during mid- to late life was also associated with a >2-fold increase in dementia risk (HR 2.40, 95% CI 1.39–4.15).

Elevated blood pressure during midlife, persistence of elevated blood pressure into late life, and, among nonhypertensives, a steep decline in blood pressure during mid- to late life were associated with an increased dementia risk in a community-based cohort. Our data highlight the potential sustained cognitive benefits of lower blood pressures in midlife but also suggest that declining blood pressure in older adults with prehypertension or normotension, but not in those with hypertension, may be a risk marker for dementia.