01/18/2012 03:21 pm ET Updated Mar 19, 2012

Does Alcohol Help Prevent Alzheimer's?

I have always been a lightweight when it comes to drinking. It only takes one or two glasses of wine to get me tipsy. One of my college roommates speculated that I might be afflicted with some type of anti-social disease that made me allergic to alcohol. It turns out that this "affliction" may have been protecting my brain from Alzheimer's all along.

Research has shown an association between drinking alcohol in moderation and having a lower risk for developing Alzheimer's disease. A recent study including almost 15,000 participants found that light drinkers had a nearly 30 percent lower risk for dementia when compared to people who either abstained completely or who overindulged. This was not a double-blind placebo controlled study, so it is not absolute proof that moderate drinking protects the brain, but it is still nice to know that while enjoying one glass of wine at dinner, there's a possibility that it's protecting my brain.

Too much alcohol, however, has been shown to be harmful to the brain, and just how much is too much varies according to the particular study. Some studies suggest that one glass of wine or spirits is brain protective for women and two glasses are the healthy brain limit for men. This difference between the sexes may simply reflect the fact that men are usually larger than women and can therefore tolerate more alcohol.

Some experts suggest that light alcohol consumption lowers the risk for Alzheimer's because of its associated lifestyle habits. People who drink in moderation may deal with many other aspects of their lives in moderation, and that personality style might protect their brains from chronic stress -- another risk factor for Alzheimer's disease.

Another possibility is that a chemical in an alcoholic beverage protects the brain, while too much of this chemical does not. Scientists at Mount Sinai School of Medicine in New York studied the effects of wine on experimental laboratory mice that possessed a human Alzheimer's gene. They found that when the mice ingested moderate amounts of Cabernet Sauvignon wine -- the mouse-equivalent of a six-ounce glass -- the animals had better memory ability and less of the protein building-blocks that lead to amyloid plaques in the brain.

Small amounts of wine, beer and hard liquor all appear to lower risk for Alzheimer's disease. The antioxidant chemicals in alcohol could protect the brain, and wine drinkers may benefit from an additional healthy brain compound found in grapes called resveratrol, which increases life span in animals similar to caloric restriction. Some researchers believe that a person might have to consume too much wine to reap the healthy brain benefits of resveratrol, but the exact amount is not known. Scientists have finally succeeded in squeezing this ingredient out of the wine bottle and into a capsule, so we all can live longer and better by taking resveratrol capsules. It's not yet clear whether the needed ingredient actually reaches the brain in capsule form, so wine lovers will be happy to know that they may still need to wash down their resveratrol capsules with a nice glass of Bordeaux.

For more by Gary W. Small, M.D., click here.

For more on Alzheimer's disease, click here.

Gary Small, M.D., is director of UCLA's Longevity Center and co-author of "The Alzheimer's Prevention Program: Keep Your Brain Healthy for the Rest of Your Life."