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Objectives: To investigate the association between daily sleep duration and risk of dementia and death in a Japanese elderly population. Design: Prospective cohort study. Setting: The Hisayama Study, Japan. Participants: Community‐dwelling Japanese individuals aged 60 and older without dementia. Measurements: Self‐reported daily sleep duration was grouped into 5 categories (<5.0, 5.0–6.9, 7.0–7.9, 8.0–9.9, ≥10.0 hours). The association between daily sleep duration and risk of dementia and death was determined using a Cox proportional hazards models. Results: During follow‐up, 294 participants developed dementia, and 282 died. Age‐ and sex‐adjusted incidence rates of dementia and all‐cause mortality were significantly greater in subjects with daily sleep duration of less than 5.0 hours and 10.0 hours and more than in those with daily sleep duration of 5.0 to 6.9 hours. These associations remained unchanged after adjustment for potential confounding factors (<5.0 hours: hazard ratio (HR)=2.64, 95% confidence interval (CI)=1.38–5.05 for dementia; HR=2.29, 95% CI=1.15–4.56 for death; ≥10.0 hours: HR=2.23, 95% CI=1.42–3.49 for dementia; HR=1.67, 95% CI=1.07–2.60 for death). Similar U‐shaped associations were observed for Alzheimer's disease and vascular dementia. With regard to the influence of hypnotic use on risk of dementia and death, subjects who used hypnotics and had any sleep duration had a risk of dementia that was 1.66 times as great and a risk of death that was 1.83 times as great as those who did not use hypnotics and had a daily sleep duration of 5.0 to 6.9 hours. Conclusion: Short and long daily sleep duration and hypnotic use are risk factors for dementia and death in Japanese elderly adults. [ABSTRACT FROM AUTHOR]

OBJECTIVES: To clarify the association between midlife and late-life smoking and risk of dementia. DESIGN: Prospective cohort study. SETTING: The Hisayama Study, Japan. PARTICIPANTS: Japanese community-dwellers without dementia aged 65 to 84 (mean age 72) followed for 17 years (1988-2005) (N = 754), 619 of whom had participated in a health examination conducted in 1973-74 (mean age, 57) and were included in the midlife analysis. MEASUREMENTS: The risk estimates of smoking status on the development of dementia were computed using a Cox proportional hazards model. RESULTS: During follow-up, 252 subjects developed all-cause dementia; 143 had Alzheimer's disease (AD), and 76 had vascular dementia (VaD). In late life, the multi-variable-adjusted risk of all-cause dementia was significantly greater in current smokers than in never smokers; similar associations were seen for all-cause dementia, AD, and VaD in midlife current smokers. Meanwhile, no significant association was observed between past smoking and risk of any type of dementia in late or midlife. Multivariable analysis showed that smokers in midlife and late life had significantly greater risks than lifelong nonsmokers of all-cause dementia (adjusted hazard ratio (aHR) = 2.28, 95% confidence interval (CI) = 1.49-3.49), AD (aHR = 1.98, 95% CI = 1.09-3.61), and VaD (aHR = 2.88, 95% CI = 1.34-6.20). Such associations were not observed for midlife smokers who quit smoking in late life. CONCLUSION: Persistent smoking from mid- to late life is a significant risk factor for dementia and its subtypes in the general Japanese population. [ABSTRACT FROM AUTHOR]

Objectives To determine the effect of milk and dairy intake on the development of all-cause dementia and its subtypes in an elderly Japanese population. Design Prospective cohort study. Setting The Hisayama Study, Japan. Participants Individuals aged 60 and older without dementia (N = 1,081). Measurements Milk and dairy intake was estimated using a 70-item semiquantitative food frequency questionnaire grouped into quartiles. The risk estimates of milk and dairy intake on the development of all-cause dementia, Alzheimer's disease ( AD), and vascular dementia (VaD) were computed using a Cox proportional hazards model. Results Over 17 years of follow-up, 303 subjects developed all-cause dementia; 166 had AD, and 98 had VaD. The age- and sex-adjusted incidence of all-cause dementia, AD, and VaD significantly decreased as milk and dairy intake level increased ( P for trend = .03 for all-cause dementia, .04 for AD, .01 for VaD). After adjusting for potential confounders, the linear relationship between milk and dairy intake and development of AD remained significant ( P for trend = .03), whereas the relationships with all-cause dementia and VaD were not significant. The risk of AD was significantly lower in the second, third, and fourth quartiles of milk and dairy intake than in the first quartile. Conclusion Greater milk and dairy intake reduced the risk of dementia, especially AD, in the general Japanese population. [ABSTRACT FROM AUTHOR]