Light-to-moderate alcohol consumption reduces the risk of coronary heart disease and stroke.
As vascular disease is associated with cognitive impairment and dementia, alcohol consumption might also affect the risk of dementia.
Monique Breteler and colleagues from Erasmus University Medical School, Rotterdam, Netherlands, examined the relation between alcohol consumption and the risk of dementia in individuals taking part in the Rotterdam Study. This prospective population-based study included around 8000 individuals, aged 55 years and older.
Participants who did not have dementia at the start of the study (from 1990 to 1993) and who had complete data on alcohol consumption were studied.
Adjusting for age, sex, systolic blood pressure, education, smoking, and body-mass index, the investigators compared the risk of developing dementia between individuals who regularly consumed alcohol with those who did not consume alcohol.
The average follow-up was 6 years.
| Light-to-moderate alcohol consumption associated with a 42% risk reduction of all dementia.
During this period, 197 individuals developed dementia (146 Alzheimer's disease, 29 vascular dementia, and 22 other dementia). The average alcohol consumption was 0.29 drinks per day.
Light-to-moderate alcohol consumption (1 to 3 drinks per day) was associated with a 42% risk reduction of all dementia, and around a 70% reduction in risk of vascular dementia.
Risk reduction was not related to the type of alcoholic drink consumed.
The investigators suggest that several mechanisms could explain the study findings.
Firstly, alcohol might reduce the cardiovascular risk profile - ethanol is known to reduce platelet aggregation - or by altering the blood-lipid ratio.
Secondly, they suggest that light-to-moderate alcohol intake might have a direct effect on cognition by stimulating the release of acetylcholine in the hippocampus area of the brain.
Acetylcholine is known to facilitate memory and learning processes; however, high alcohol intake inhibits acetylcholine production.
Dr Breteler comments, "In recent years evidence has been accumulating that vascular factors may be involved in the cause of dementia, both vascular dementia and Alzheimer's disease.
"Our findings lend further support to the vascular hypothesis of dementia.
"We saw some indication for a stronger relation with alcohol in persons with a genetically determined susceptibility for Alzheimer's disease."
"Our findings can help focus research into the specific mechanisms that underlie the development of dementing illnesses," she concluded.