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Midlife and Late‐Life Smoking and Risk of Dementia in the Community: The Hisayama Study
Author(s) -
Ohara Tomoyuki,
Ninomiya Toshiharu,
Hata Jun,
Ozawa Mio,
Yoshida Daigo,
Mukai Naoko,
Nagata Masaharu,
Iwaki Toru,
Kitazono Takanari,
Kanba Shigenobu,
Kiyohara Yutaka
Publication year - 2015
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1111/jgs.13794
Subject(s) - medicine , dementia , hazard ratio , vascular dementia , proportional hazards model , cohort study , confidence interval , risk factor , gerontology , cohort , prospective cohort study , population , disease , environmental health
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 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. Conclusion Persistent smoking from mid‐ to late life is a significant risk factor for dementia and its subtypes in the general Japanese population.