Light to moderate consumption of alcohol may help maintain cognitive ability in elderly women, according to a study of more than 11,000 women in their 70s and early 80s.
"Our data suggests that, in women, up to one drink per day does not impair cognitive function and may actually decrease the risk of cognitive decline," wrote the authors of the study, published in the Jan. 20 issue of the New England Journal of Medicine. The team was headed by Meir Stampfer, a professor of epidemiology at Harvard School of Public Health in Boston, whose previous work has found that moderate drinking reduces the risk of heart attacks and strokes in women.
According to the researchers, the harmful effects of heavy drinking on brain function have been well established, but the effects of moderate drinking--defined as one drink per day for women--have been less clearly defined. Because moderate drinking is strongly linked to a reduced rate of cardiovascular disease, which shares common risk factors with cognitive dysfunction, the scientists wanted to determine if a similar link exists for brain deterioration.
Their results add support to previous research that has found that moderate drinking may not be linked to cognitive decline, may actually reduce brain deterioration in elderly women or may even be related to better cognitive skills.
Stampfer's team looked at 11,102 participants from the Nurses' Health Study, which has been ongoing since 1976. That study has tracked the health and lifestyle--including alcohol consumption and preferred beverage--of 121,700 registered nurses through questionnaires filled out every two years. The women were categorized by their alcohol consumption levels: nondrinkers, 1 gram to 14.9 grams of alcohol per day, 15 grams to 30 grams per day, and more than 30 grams per day. (A typical drink contains around 12 grams of alcohol.)
In 1995, Stampfer and his team recruited volunteers from the study who were 70 years or older and who had not changed drinking habits. (Heavy drinkers were excluded.) The women's cognitive functions were rated using various tests, such as naming as many animals as they could recall in a set time frame or repeating a series of numbers backwards. The tests were repeated two years later in order to chart decline, if any. Poor cognition was defined as scoring at or below the 10th percentile.
Stampfer and his team then compared test results to the women's drinking habits and adjusted for several factors, such as cigarette smoking, use of vitamin E supplements, energy levels and age at the onset of menopause.
The women who drank up to 14.9 grams per day--the light to moderate category--showed about a 20 percent lower risk for cognitive decline than nondrinkers. There was "no marked difference according to type of beverage," the researchers wrote. The women who drank 15 grams to 30 grams per day showed the same rate of cognitive decline as the nondrinkers.
Those results suggest "that the degree of protection from 1 gram to 14.9 grams per day of alcohol is the cognitive equivalent of being about one and one-half years younger," said R. Curtis Ellison M.D., an epidemiologist at the Boston University School of Medicine. He was not involved with the Stampfer study, but reviewed the findings.
Stampfer's team cautioned that other factors could have affected the study results. For example, they noted that light drinkers tended to lead healthy lives, which may lend a protective effect to the brain as well. And alcohol consumption was self-reported; therefore a person with brain deterioration may erroneously report their drinking levels.
Furthermore, the researchers warned against changing one's drinking habits based on the study. "Caution should be exercised in recommending even moderate alcohol intake," they said.