Women who imbibe a little wine, beer or even spirits every day are less likely than teetotalers to see their memories and other thinking powers fade as they age, according to the largest study to assess alcohol's impact on the brain.
The study of more than 12,000 elderly women found that those who consumed light to moderate amounts of alcohol daily had about a 20 percent lower risk of experiencing problems with their mental abilities later in life.
"Low levels of alcohol appear to have cognitive benefits," said Francine Grodstein of Brigham and Women's Hospital in Boston, senior author on the study, published in today's New England Journal of Medicine. "Women who consistently were drinking about one-half to one drink per day had both less cognitive impairment as well as less decline in their cognitive function compared to women who didn't drink at all," Grodstein said.
While the study involved only women, the findings probably hold true for men, although previous research indicates that men seem to benefit from drinking slightly more -- one to two drinks per day, researchers said.
The findings provide the latest evidence that indulging in alcohol, long vilified as part of an insalubrious lifestyle, can actually help people live longer, healthier lives. While heavy drinking clearly causes serious problems for many people, recent research has found that drinking in moderation protects the heart. A few small studies have similarly suggested that alcohol may help the brain. The new study is by far the largest and most detailed to examine that question.
"We know it is beneficial to have a drink a day for your heart. This says there is an additional reason to follow that guideline -- it can protect against cognitive decline," said Marilyn S. Albert of the Johns Hopkins University School of Medicine, speaking on behalf of the Alzheimer's Association. "So now we have two reasons to do it."
Alcohol appears to protect the brain in the same way that it guards the heart: by improving blood flow. It may also reduce the risk of small "silent" strokes, which can cause subtle brain damage that erodes mental powers.
For the new study, researchers analyzed data on about 12,480 women ages 70 to 81 participating in the Nurses' Health Study, in which detailed information is being gathered about thousands of nurses as they age to try to assess how myriad lifestyle factors affect health.
Data on alcohol consumption had been gathered regularly beginning when the women were in their forties and fifties. They also underwent detailed questioning by telephone when they reached their seventies to assess their ability to remember and reason and to perform other mental functions.
Those who consumed half a drink to one drink each day for at least four years were about 20 percent less likely to have an impairment in their thinking abilities and about 15 percent less likely to experience a decline in their mental powers over the two years they were studied, regardless of what type of alcohol they preferred, the researchers found. On average, women who drank moderately tended to have the memory and reasoning agility of someone about a year and a half younger than those who abstained. No benefit was seen among women who drank more than that.
The results held true even after the researchers factored in characteristics about the women that could have confused the findings, such as age, education, how many friends and family members they had, how much exercise they got, and whether they had any other health problems.
While the findings are encouraging, several researchers said they were concerned about strongly recommending that people drink more based on the results, given the heavy toll from alcohol abuse.
"The prevention of cognitive decline in old age . . . is one of the major public health challenges of the 21st century. Few things are as valuable as the unimpaired ability to reason," Denis A. Evans of Rush University in Chicago wrote in an editorial accompanying the study. But "persons seeking to maximize cognition in old age must keep in mind . . . the knowledge that alcohol consumption can be a double-edged sword, with the dangers of over-indulgence being all too familiar."
Elderly people are at particular risk for experiencing problems from drinking, such as falls, which can be life-threatening, said Molly V. Wagster of the National Institute on Aging. But Wagster added that the weight of the evidence clearly indicates that moderate alcohol consumption cuts the risk for dementia.
"The preponderance of the observational evidence certainly points in that direction," Wagster said.
The findings suggest that moderate drinking should join the growing list of steps that people can take to try to stave off mental decline, such as getting regular physical exercise and routinely engaging in mentally stimulating activities, Albert said.
"The basic message is, there is a lot we can do to lower our risk for cognitive decline," she said. "I would add having a drink a day to that."