Alcohol consumption, smoking, and risk of dementia in community-dwelling Japanese people aged 40-74 years

Alcohol drinking and tobacco smoking have impacts on lifestyle-related diseases, but their association with dementia remains a debated topic. A study aimed to examine longitudinal associations between alcohol consumption, smoking, and dementia risk in middle-aged and older Japanese people.
A cohort design was employed, with an 8-year follow-up. Participants were 13,802 community-dwelling Japanese people aged 40-74 years. The baseline survey, including a self-administered questionnaire, was conducted in 2011-2013. Predictors were alcohol consumption and tobacco smoking. The outcome was incident dementia obtained from a long-term care insurance database. Covariates were demographics, lifestyle factors, body mass index, general health status, and history of stroke, diabetes, and depression.
Participants had a mean age of 59 years. The 1-149, 150-299, and 300-449 g ethanol/week groups had significantly lower adjusted hazard ratios (HRs) (0.62, 0.59, and 0.47, respectively) compared with the reference group, with no significant linear association. HRs increased toward 1 when past-drinkers and those with poor health status and a disease history were excluded (0.80, 0.66, and 0.82, respectively). Higher smoking levels were dose-dependently associated with a higher HR, with the ≥20 cigarettes/day group having a significantly higher adjusted HR (1.80). Heavy drinkers (≥449 g ethanol/week) with smoking habits, but not those without smoking habits, had higher dementia risk.
Light-to-moderate alcohol consumption was associated with decreased dementia risk, and smoking was dose-dependently associated with increased dementia risk, with an interaction between high alcohol consumption and smoking on dementia risk.
Source: Kawakami S, Yamato R, Kitamura K, Watanabe Y, Kabasawa K, Takahashi A, Saito T, Kobayashi R, Oshiki R, Takachi R, Tsugane S, Yamazaki O, Watanabe K, Nakamura K. Alcohol consumption, smoking, and risk of dementia in community-dwelling Japanese people aged 40-74 years: The Murakami cohort study. Maturitas. 2023 Jun 14;176:107788. .