Aug. 17, 2011 -- Moderate alcohol consumption may help stave off memory problems and/or Alzheimer's disease, a study shows.
Researchers reviewed 143 studies comprising more than 365,000 participants from 19 countries. Their analysis is published in Neuropsychiatric Disease and Treatment.
Moderate drinking is defined as a maximum of one drink daily for women and two drinks daily for men. A standard drink is defined as 1.5 ounces of spirits, 5 ounces of wine, or 12 ounces of beer.
Overall, moderate drinkers were 23% less likely to develop signs of memory problems or Alzheimer's disease. These benefits were seen in 14 of 19 countries, including the U.S., the study showed.
"This study is not the final word, but it does provide the most complete picture out there," says study researcher Michael A. Collins, PhD, of the department of molecular pharmacology and therapeutics at Loyola University Medical Center in Maywood, Ill.
Exactly how moderate alcohol consumption may lower risk for memory problems is not fully understood, but alcohol may have anti-inflammatory effects. Inflammation in the brain is thought to play a role in Alzheimer's disease, which is the most common form of dementia. Inflammation has also been implicated in heart disease, stroke, diabetes, rheumatoid arthritis, and even some cancers.
The buzz word is neuroinflammation, and alcohol, in moderate amounts, may suppress neuroinflammation, but higher levels of alcohol may stimulate it, Collins says.
Drinkers vs. Non-Drinkers
Researchers reviewed 143 studies dating back as far as 1977. Of these, 74 compared risk between non-drinkers and drinkers and 69 looked at whether memory was better, worse, or equal among drinkers and non-drinkers. Moderate drinkers had a lower risk for dementia compared to non-drinkers. The benefit was the same among men and women.
Wine seemed to be more protective than beer or spirits, according to the new report. But most of the studies did not differentiate between types of alcohol so it would be premature to draw such a conclusion.
Heavy alcohol consumption or more than three to five drinks per day did show a trend of increased risk for memory problems and dementia in the study, but this finding did not reach statistical significance.
Christy Tangney, PhD, an associate professor of clinical nutrition at Rush University Medical Center in Chicago, says that moderation is the key.
"It is a friendly balancing act," she says.
"Social drinking can be a very positive thing as long as it is not excessive and doesn't exceed a drink per day for women or two drinks for men," Tangney says. "Light-to-moderate drinking appears to benefit cognitive performance."
Negative Effects of Alcohol
But "non-drinkers should not take a drink for this purpose," Tangney says.
William H. Thies, PhD, the chief medical and scientific officer of the Alzheimer's Association in Chicago, agrees that it is too difficult to make a blanket recommendation about moderate alcohol consumption for Alzheimer's disease prevention.
"Moderate alcohol consumption is associated with positive effects in a number of disease states," he says. But Thies cautions that this doesn't mean that it is safe to make a general recommendation for everyone to drink in moderation because we don't know what the health consequences would be.
"A portion of the population is predisposed to alcoholism and if they are teetotalers, they will never express this tendency. But if given instructions to drink for their health, they likely won't stop at the moderate stage," he says.