"Our research confirms other studies suggesting that for older women who choose to drink - and are not restricted from drinking for medical reasons - moderate alcohol intake is not harmful for cognition and may provide some mental benefits," said Mark Espeland, Ph.D., lead author.
The study, available on-line in the journal Neuroepidemiology, found that compared to non-drinkers, women who reported drinking up to two or three drinks per day performed better on measure of global cognitive function, which includes concentration, language, memory and abstract reasoning. The women were strongest in verbal skills: those who reported having at least one drink a day did better on vocabulary tests and on a word fluency test asking them to generate a list of words beginning with a specific letter.
Espeland, a professor of public health sciences and chairman of the Department of Biostatistical Sciences, said understanding whether alcohol affects specific areas of cognition may shed light on the mechanisms that make it protective. Possible mechanisms include that alcohol increases levels of "good" cholesterol and lowers the risk of stroke, that it may decrease the formation of plaque that is associated with Alzheimer's disease and that it may increase the release of brain chemicals that affect learning and memory.
He said that until scientists know more, women shouldn't change their drinking patterns. "Until we better understand the reasons why alcohol consumption is associated with better cognitive functioning, these results on their own are not a reason for people who don't drink to start or for those who drink to increase their intake."
The researchers used data from the 7,460 women enrolled in the Women's Health Initiative Memory Study (WHIMS), a large national study to assess the effects of hormone therapy on dementia and cognitive function. They also used data from 2,299 of these women who were also enrolled in the Women's Health Initiative Study of Cognitive Aging (WHISCA), which involved annual standardized testing of specific areas of cognitive performance. All women in the studies were 65 and older.
Data from this large group of women confirmed earlier findings from the researchers (based on a subset of 4,461 WHIMS participants,) that those who drank moderate amounts of alcohol (up to two or three drinks a day) performed better on tests for cognitive function. Using data from the WHISCA participants, they were able to pinpoint specific areas of cognition that were affected.
"Findings from this large and diverse group of older women suggest that moderate levels of alcohol intake are associated with some benefit to overall cognition and that the benefit appears strongest in areas of verbal function," said Espeland.
Previous studies have also indicated that moderate levels of alcohol intake reduce the risk of dementia and decline in cognitive function. Espeland said, however, that the results must be interpreted with caution.
"While evidence is growing that alcohol is beneficial in this area, it is still unclear whether alcohol intake or another defining characteristic is the reason for reduced risk," he said.
The researchers adjusted for other factors that might affect the results, such as education level and family income, and still found the same pattern of moderate alcohol intake associated with better cognitive function and less risk of dementia.
"But we cannot rule out that unmeasured factors affected cognition," he said.
The study received support from the National Institute on Aging, a part of the National Institutes of Health at the U.S. Department of Health and Human Services.
Espeland's co-researchers were Laura Coker, Ph.D., and Stephen R. Rapp, Ph.D., also from Wake Forest Baptist, Robert Wallace, M.D., from the University of Iowa College of Medicine, Susan Resnick, Ph.D., from the National Institute on Aging, Marian Limacher, M.D., from the University of Florida, Lynda Powell, M.D., from Rush University Medical Center, and Catherine Messina, Ph.D., from State University of New York at Stony Brook.
Wake Forest University Baptist Medical Center is an academic health system comprised of North Carolina Baptist Hospital and Wake Forest University Health Sciences, which operates the university's School of Medicine. The system comprises 1,187 acute care, psychiatric, rehabilitation and long-term care beds and is consistently ranked as one of "America's Best Hospitals" by U.S. News & World Report.