In the largest such study to date, older women who drank moderately had less mental decline than those who abstained .... [R]esearchers found that light to moderate drinking of any kind of alcoholic beverage reduced the risk of mental decline by more than 20%, compared with abstinence.
Essentially, their brains were the cognitive equivalent of being 1.5 years younger....
The research, published today in the New England Journal of Medicine, adds to a couple of large, European studies that found a reduced risk of dementia in drinkers, said Diana Kerwin, an assistant professor of medicine in the division of geriatrics and gerontology at the Medical College of Wisconsin.
"You get a benefit up to (the point of) excessive alcohol intake," she said. "Alcohol is not bad."
So drink as much as you can without drinking too much. There's some line there, and good luck finding it and staying on the right side of it.