According to background information in the article, alcohol consumption has been associated with complex changes in the brain and its blood vessels in older adults. How alcohol consumption affects the incidence of dementia has been less clear. Dementia imposes a tremendous burden on patients, caregivers and society. Alzheimer disease alone causes more than 360,000 new cases in the United States annually, with a national annual cost of caring for such patients of more than $50 billion. This burden has spurred a search for modifiable factors that cause or prevent dementia.

Kenneth J. Mukamal, M.D., M.P.H., of Beth Israel Deaconess Medical Center in Boston, and colleagues performed a case-control study of alcohol consumption and risk of dementia among older adults. The study included 373 cases with new onset of dementia and 373 controls who were among 5,888 adults aged 65 years and older who participated in the Cardiovascular Health Study, a prospective, population-based cohort study in four U.S. communities. Participants in this study underwent medical evaluations, magnetic resonance imaging (MRI) of the brain, and cognitive testing between 1992 and 1994 and were followed up until 1999.

The researchers found: "Compared with abstention, the adjusted odds for dementia among those whose weekly alcohol consumption was less than one drink were 0.65 [35 percent lower risk]; one to six drinks, 0.46 [54 percent lower risk]; seven to 13 drinks, 0.69 [31 percent lower risk]; and 14 or more drinks, 1.22 [22 percent greater risk]. A trend toward greater odds of dementia associated with heavier alcohol consumption was most apparent among men and participants with an apolipoprotein E epsilon4 allele [a gene marker]. We found generally similar relationships of alcohol use with Alzheimer disease and vascular dementia."

"In conclusion, we found the lowest odds of dementia among older adults who consumed one to six drinks weekly. Given the many physiological effects associated with alcohol consumption and the observational nature of our study, our findings should be extrapolated to clinical care with great caution. However, our results are consistent with the hypothesis that light-to-moderate drinking has a protective effect on long-term cognitive function," the researchers write.