Drinking as little as one serving of an alcoholic beverage each week can lower the risk of dementia in people over the age of 65, according to a study in the March 19 issue of the Journal of the American Medical Association (JAMA).

Researchers found that older people who do not drink alcoholic beverages run twice the risk of moderate drinkers of developing dementias. Those who drink 14 or more drinks per week also had a higher risk of becoming demented than moderate drinkers. Moderate drinking was considered to be no more than six servings of alcoholic beverages a week.

The study compared the alcohol consumption patterns of 373 dementia patients with 373 control subjects who did not have dementia. Alzheimer's disease or stroke was the most common cause of dementia in the participants.

Over the course of the study, participants were asked to record the frequency and number of 12-ounce servings of beer, 6-ounce servings of wine and shots of liquor they consumed. Researchers took the average of the participants' reported alcohol use.

After adjusting for numerous factors, the researchers found a clear association between moderate alcohol consumption and reduced risk of dementia.

Moderate drinkers had a 54 percent lower risk of dementia than abstainers, while the heavier drinkers have a 22 percent higher risk of dementia than abstainers, according to study author Dr. Kenneth Mukamal, an assistant medical professor at Harvard Medical School and physician at Beth Israel Deaconess Medical Center.

Mukamal said alcohol might guard against the development of cerebral arteriosclerosis or hardening of the arteries. However, given the observational nature of the study, he could not recommend that older adults begin drinking moderately. Instead, he said older adults should discuss their alcohol use with their physicians and make appropriate decisions based on these discussions.

Other sources: Beth Israel Deaconess Medical Center, JAMA (289:1405-1413)