Background: Light-to-moderate alcohol consumption reduces the risk of coronary heart disease and stroke. Because vascular disease is associated with cognitive impairment and dementia, we hypothesised that alcohol consumption might also affect the risk of dementia.

Methods: We examined the relation between alcohol consumption and risk of dementia in individuals taking part in the Rotterdam Study--a prospective population-based study of 7983 individuals aged 55 years and older. We studied all participants who did not have dementia at baseline (1990-93) and who had complete data on alcohol consumption (n=5395). Through follow-up examinations in 1993-94 and 1997-99 and an extensive monitoring system, we obtained nearly complete follow-up (99.7%) until the end of 1999. We used proportional hazards regression analysis, adjusted for age, sex, systolic blood pressure, education, smoking, and body-mass index, to compare the risk of developing dementia between individuals who regularly consumed alcohol and individuals who did not consume alcohol.

Findings: The average follow-up was 6.0 years. During this period, 197 individuals developed dementia (146 Alzheimer's disease, 29 vascular dementia, 22 other dementia). The median alcohol consumption was 0.29 drinks per day. Light-to-moderate drinking (one to three drinks per day) was significantly associated with a lower risk of any dementia (hazard ratio 0.58 [95% CI 0.38-0.90]) and vascular dementia (hazard ratio 0.29 [0.09-0.93]). We found no evidence that the relation between alcohol and dementia varied by type of alcoholic beverage.

Interpretation: These findings suggest that light-to-moderate alcohol consumption is associated with a reduced risk of dementia in individuals aged 55 years or older. The effect seems to be unchanged by the source of alcohol.