Moderate drinking may cut dementia risk

Researchers in the Netherlands found that among the 5,400 older adults they studied, those who had up to three drinks a day were less likely than non-drinkers to develop any type of dementia, including Alzheimer's disease. And it did not matter whether the alcohol was wine, beer, liquor or a fortified wine such as sherry.

However, the relatively few who said they had four or more drinks in a day saw no such protective effect, according to findings published in the January 26th issue of The Lancet.

Past research has suggested that enjoying a drink or two a day might help ward off the mental decline that often comes with age. Since evidence also shows light-to-moderate drinking may benefit the heart, investigators have speculated that, similarly, alcohol might help maintain blood flow to the brain by reducing clotting or improving cholesterol levels.

This idea could help explain the current findings, according to Dr. Monique M. B. Breteler and colleagues at Erasmus Medical Centre in Rotterdam.

Another possibility, the authors add, is that alcohol directly affects mental functioning through the release of the chemical acetylcholine in the brain. They note that "substantial evidence" indicates that acetylcholine affects learning and memory, and rat research has shown that low levels of alcohol stimulate the chemical's release, while higher alcohol levels inhibit it.

In the study, Breteler's team followed mentally healthy men and women aged 55 and older for an average of 6 years. At the study's start, participants completed questionnaires on their diet and drinking habits during the past year, and were asked whether they had altered their drinking patterns during the previous 5 years--which only a small percentage had.

Other health factors, including age, diabetes, blood pressure and smoking, were also recorded.

During the study, 197 participants developed dementia, most often Alzheimer's disease. Those who had said they drank one to three alcoholic beverages a day were 42% less likely to develop any type of dementia, regardless of the other health factors. They were 70% less likely than non-drinkers to be diagnosed with vascular dementia, an impairment caused by significant reductions in the brain's blood supply.

In addition, a couple of drinks per day showed a protective effect among people who carried the gene variant ApoE4, which is associated with an increased Alzheimer's risk. The researchers speculate that alcohol, possibly through improving cholesterol levels, might moderate dementia risk among ApoE4 carriers.

"Further studies are needed to clarify the relation between (ApoE) and alcohol consumption," Breteler and colleagues conclude.