A population-based prospective study in Bordeaux, France, reported an inverse association between wine consumption and the risk of dementia. In this study, Monique Breteler et al hypothesised that light-to-moderate alcohol intake was associated with a lower risk of dementia, and aimed to quantify the relation between alcohol consumption and the risk of dementia and subtypes of dementia; specifically, and examined whether the effect varied by type of alcoholic beverage.

Monique Breteler et al studied individuals taking part in the Rotterdam Study–a prospective population-based study of 7983 individuals aged 55 years and older. All participants who did not have dementia at baseline (1990-93) and who had complete data on alcohol consumption (n=5395) were included. Through follow-up examinations in 1993-94 and 1997-99 and an extensive monitoring system, nearly complete follow-up (99·7%) until the end of 1999 was achieved. Proportional hazards regression analysis was used, 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. To check whether associations could be attributed to confounding, analyses were repeated with possible confounders added to the models (education, smoking, body-mass index, diabetes, and systolic blood pressure). All analyses were repeated with dementia subtypes (Alzheimer’s disease, vascular dementia) as the outcome.

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). Light-to-moderate drinking (one to three drinks per day) was significantly associated with a lower risk of any dementia and vascular dementia. No evidence was found that the relation between alcohol and dementia varied by type of alcoholic beverage. With increasing alcohol intake, the proportion of never smokers and less-educated individuals sharply decreased. Beer and liquor were mainly consumed by men. Fortified wine was mainly consumed by women.

Compared with no alcohol consumption, light-to-moderate drinking (one to three drinks per day) was associated with a significantly lower risk of dementia. The effect of light-to-moderate drinking seemed more prominent among men. There was no significant interactions with age, smoking, or level of education.

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. the researchers found that, in a population aged 55 years or older, those who consumed up to three glasses of alcohol per day had a lower risk of dementia and vascular dementia than those who never drank alcohol

Several mechanisms could be responsible for the inverse relation between consumption of up to three alcoholic drinks a day and dementia. One possibility is that alcohol might act through reduction of cardiovascular risk factors, either through an inhibitory effect of ethanol on platelet aggregation, or through alteration of the serum lipid profile. The findings that the lower risk was seen mainly for vascular dementia is in agreement with this hypothesis. A second possibility is that alcohol might have a direct effect on cognition through release of acetylcholine in the hippocampus. There is substantial evidence that acetylcholine facilitates learning and memory.

Previously, the PAQUID study in Bordeaux, France, reported that wine consumption is associated with a lower risk of dementia, but the Rotterdam data did not suggest a different effect of specific types of alcoholic beverages beyond the effect of alcohol itself. The observations are consistent with recent findings of the Canadian Study of Health and Ageing.

Alcohol consumption and risk of dementia: the Rotterdam Study Volume 359, Number 9303 26 January 2002 The Lancet Monique M B Breteler et al Department of Epidemiology and Biostatistics s Correspondence to: Dr Monique M B Breteler (e-mail:breteler@epib.fgg.eur.nl)