Researchers at the Wake Forest University Baptist Medical Center in the US report from their study that women aged between 65 to 79 years, who consumed between one or two drinks a day, tended to perform better on tests for cognitive function and dementia.
"Women who reported drinking one or more drinks a day had a 40 per cent lower risk of significant declines in cognitive function over time, compared to women who reported no alcohol intake," said lead researcher Mark Espeland, a professor of public health sciences.
A growing body of science has highlighted the possible benefits to mental health - reducing the risk of dementia and the decline in cognitive function - of moderate drinking. Much work has focused on the red wine compound resveratrol, thought to be responsible for the drink's protective effects on the heart.
Dementia already affects millions around the world and the threat is increasing with the growing numbers of elderly. Alzheimer's disease, the leading cause of dementia in the elderly, afflicts an estimated 4.5 million people in the US alone.
"There are a number of reasons one might expect moderate alcohol intake to be beneficial," says Espeland, who, with his team, tracked 4,461 women aged 65 to 79 years for an average of 4.2 years with annual Modified Mini-Mental State Examinations (MMSE).
"Some cognitive problems are due to strokes and blood vessels in the brain becoming blocked, and alcohol may reduce the development of blood clots and increase blood flow, thereby improving cognition."
The scientists added that 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.
But despite growing evidence, scientists still remain unsure as to whether alcohol intake or another defining characteristic is the reason for reduced risk.
The researchers said that even adjusting for other factors that might affect the results, such as education level and family income, they 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," warns Espeland.
" 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."
Full findings of this latest study are published in the February 1 issue (Vol. 161, pages 228-38) of the American Journal of Epidemiology.