Midlife and late-life smoking and risk of dementia in the community: The Hisayama study

Tomoyuki Ohara, Toshiharu Ninomiya, Jun Hata, Mio Ozawa, Daigo Yoshida, Naoko Mukai, Masaharu Nagata, Toru Iwaki, Takanari Kitazono, Shigenobu Kanba, Yutaka Kiyohara

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48 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)2332-2339
Number of pages8
JournalJournal of the American Geriatrics Society
Issue number11
Publication statusPublished - Nov 2015

All Science Journal Classification (ASJC) codes

  • Geriatrics and Gerontology


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