Lifestyle and the risk of dementia in Japanese-american men.

OBJECTIVES: To determine whether adhering to a healthy lifestyle in midlife may reduce the risk of dementia.

DESIGN: Case-control study nested in a prospective cohort.

SETTING: The Honolulu-Asia Aging Study, Oahu, Hawaii.

PARTICIPANTS: Three thousand four hundred sixty-eight Japanese-American men (mean age 52 in 1965-1968) examined for dementia 25 years later.

MEASUREMENTS: Men at low risk were defined as those with the following midlife characteristics: nonsmoking, body mass index (BMI) less than 25.0 kg/m(2) , physically active, and having a healthy diet (based on alcohol, dairy, meat, fish, fruits, vegetables, cereals, and ratio of monounsaturated to saturated fat). Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for developing overall dementia, Alzheimer's disease (AD), and vascular dementia (VaD), adjusting for potential confounders.

RESULTS: Dementia was diagnosed in 6.4% of men (52.5% with AD, 35.0% with VaD). Examining the risk factors individually, BMI was most strongly associated with greater risk of overall dementia (OR = 1.87, 95% CI = 1.26-2.77; BMI > 25.0 vs <22.6 kg/m(2) ). All of the individual risk factors except diet score were significantly associated with VaD, whereas none were significantly associated with AD alone. Men with all four low-risk characteristics (7.2% of the cohort) had the lowest OR for overall dementia (OR = 0.36, 95% CI = 0.15-0.84). There were no significant associations between the combined low-risk characteristics and the risk of AD alone.

CONCLUSION: Among Japanese-American men, having a healthy lifestyle in midlife is associated with a lower risk of dementia in late life.