Defined in the study as less than one drink a day, low to moderate drinking was associated with a significantly slower progression to dementia among people with mild age-related cognitive declines, compared with nondrinkers.
The protective benefit was not seen with higher alcohol consumption.
The research was part of a larger Italian study designed to determine if the healthful aspects of the traditional Mediterranean diet can help protect aging people from Alzheimer's disease and other forms of mental decline. Earlier findings from the study suggest that specific staples of the diet, including olive oil, whole grains, and red wine, can help protect aging brains.
Researcher Vincenzo Solfrizzi, M.D., Ph.D., tells WebMD that these dietary influences may act synergistically to slow mental decline, possibly by reducing the blood vessel inflammation thought to contribute to Alzheimer's disease.
The Italian research is not the first to suggest a protective role for low-to-moderate alcohol consumption against age-related mental decline. But it is among the first to focus on elderly people who already have early signs of cognitive impairment.
The study included 1,445 elderly Italians without mental decline and 121 elderly Italians with a diagnosis of mild cognitive impairment (MCI) — considered a state between normal aging and dementia. Patients with MCI who said they did drink alcohol but drank less than one drink a day had an 85% lower rate of progression to dementia over 3.5 years of follow up than nondrinkers.
A drink was considered to have 0.5 ounces of alcohol — the amount typically found in a 12-ounce glass of regular beer, a 5-ounce glass of wine, or a cocktail containing 1 ounce of spirits.
Alcohol consumption did not appear to influence progression to MCI in the nonimpaired study participants. And having a drink a day or more did not appear to slow progression to dementia in the patients with MCI.
The study is published in the May 22 issue of the journal Neurology.
While only very low alcohol consumption seemed to protect aging brains in the Italian subjects, other studies have suggested a protective benefit for higher levels of drinking.
One notable study — from Bordeaux, France — found three to four glasses of wine a day to be optimal for reducing age-related dementia risk. Most other positive studies have shown benefits for much lower consumption.
Solfrizzi says he advises his elderly patients who drink to restrict their alcohol consumption to one or two drinks a day.
Mayo Clinic neurologist Ron Petersen, M.D., tells WebMD that the studies examining the role of alcohol and age-related mental decline fall far short of proving a protective benefit. Petersen is a fellow with the American Academy of Neurology.
"Methodologically, these are not easy studies to do," he says. "Even if people are honest about how much they drink, their memories may not be accurate."
He says one alcoholic drink a day is "probably safe and may be beneficial" for most elderly people concerned about dementia. "That is a conservative interpretation of the research, but it is probably more accurate than not," he says.
By Salynn Boyles
Reviewed by Louise Chang
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