Association between late-life blood pressure and incident dementia in older men: The Kuakini Honolulu-Asia aging study

Background The relationship between late-life blood pressure and incident dementia (including Alzheimer's disease and vascular dementia) remains controversial. Objective To examine whether late-life blood pressure is associated with incidence of dementia. Methods We analyzed 2649 participants aged 71 to 93 years without prevalent dementia at baseline in a prospective cohort of Japanese-American men (the Kuakini Honolulu Heart Program). Diagnosis of dementia was conducted based on standardized protocols and participants were followed for up to 20 years. Cox proportional hazards models were applied to estimate hazard ratios (HR) for incident dementia across blood pressure categories, adjusting for demographic, medical, lifestyle, and genetic factors. Results During follow-up, 716 cases of incident dementia were identified (519 cases of Alzheimer's disease and 88 cases of vascular dementia). After adjustment, high late-life systolic blood pressure (≥160 mmHg) was associated with a lower risk of Alzheimer's disease [HR 0.72 (95% confidence interval: 0.56–0.93)] and a higher risk of vascular dementia [HR 1.95 (95% confidence interval: 1.03–3.68)] compared to the reference (120 to <140 mmHg) group. The protective effect of high late-life systolic blood pressure (≥160 mmHg) on Alzheimer's disease was seen only in participants with the protective version of the FOXO3 genotype. No significant associations were found between diastolic blood pressure and incidence of dementia. Conclusions High late-life systolic blood pressure was associated with a protective effect against Alzheimer's disease, after adjusting for confounders, including the FOXO3 longevity genotype, and an increased risk of vascular dementia in older men aged over 71 years.