Espeland said alcohol also tends to increase levels of high-density lipoprotein, or "good" cholesterol, which might also reduce the risk for narrowed vessels in the brain. In addition, alcohol may decrease the formation of plaque that is associated with Alzheimer's disease.
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. "My sense is 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 benefits by reducing the risk of cognitive decline.
"Until we better understand the reasons why alcohol consumption is associated with better cognitive functioning, however, these results on their own are not a reason for people who don't drink to start or for those who drink less to increase their intake."
Espeland's co-researchers were Lin Gu, M.S., Laura Coker, Ph.D., and Stephen R. Rapp, Ph.D., also from Wake Forest Baptist, Kamal H. Masaki, M.D., from the University of Hawaii, Robert D. Langer, M.D., M.P.H., from the University of California at San Diego School of Medicine, Marcia L. Stefanick, Ph.D., from Stanford University School of Medicine, and Judith Ockene, Ph.D.
Contact: Karen Richardson
Wake Forest University Baptist Medical Center