Edward J. Neafsey and Michael A. Collins, professors in the department of molecular pharmacology and therapeutics at Loyola University Chicago Stritch School of Medicine, analyzed 143 studies dating from 1977 that involved more than 365,000 study participants.
The study, published in the journal Neuropsychiatric Disease and Treatment, finds moderate drinkers were 23 percent less likely to develop cognitive impairment or Alzheimer's disease and other forms of dementia. Wine was more beneficial than beer or spirits, but most papers did not distinguish among different types of alcohol.
Heavy drinking -- more than three to five drinks per day -- was associated with a higher risk of cognitive impairment and dementia, but this finding was not statistically significant, the study says.
"We don't recommend that non-drinkers start drinking," Neafsey says in a statement. "But moderate drinking -- if it is truly moderate -- can be beneficial."
The study found the protective effect of moderate drinking held up after adjusting for age, education, sex and smoking. There was no difference in the effects of alcohol on men and women and the beneficial effect of moderate drinking was seen in 14 of 19 countries, including the United States.
Researchers found a benefit in three of the remaining five countries but it was not statistically significant.