Midlife and Late-Life Smoking and Risk of Dementia in the Community: The Hisayama Study.
OBJECTIVE
To clarify the association between midlife and late-life smoking and risk of dementia.


METHODS
Prospective cohort study.


METHODS
The Hisayama Study, Japan.


METHODS
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.


METHODS
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 multivariable-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.


CONCLUSIONS
Persistent smoking from mid- to late life is a significant risk factor for dementia and its subtypes in the general Japanese population.
Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.|Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Tomoyuki
T
Ohara
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.|Department of Center for Cohort Studies, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Toshiharu
T
Ninomiya
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.|Department of Center for Cohort Studies, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Jun
J
Hata
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Mio
M
Ozawa
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.|Department of Center for Cohort Studies, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Daigo
D
Yoshida
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.|Department of Center for Cohort Studies, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Naoko
N
Mukai
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Masaharu
M
Nagata
Department of Neuropathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Toru
T
Iwaki
Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Takanari
T
Kitazono
Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Shigenobu
S
Kanba
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Yutaka
Y
Kiyohara
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000209:etiology; D015331:Cohort Studies; D003704:Dementia / Q000209:etiology*; D015140:Dementia, Vascular / Q000209:etiology; D005260:Female; D006801:Humans; D057187:Independent Living; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects*
Alzheimer's disease; cohort studies; dementia; smoking; vascular dementia