For those trying to follow preventative advice to avoid dementia, the guidance on drinking alcohol is a little murky. Some studies say that a glass of red wine per day helps ward off Alzheimer’s; other studies have found that even a small amount of alcohol can contribute to the likelihood of developing the disease. But a new study offers more evidence on one point most research agrees with: Binge drinking could increase the risk of dementia.
Researchers from the University of Illinois at Chicago discovered that some of the genes that alcohol inhibits are the same genes responsible for clearing beta-amyloid, the protein that builds up into plaques in the brains of Alzheimer’s patients. The plaques keep neurons from communicating with each other and eventually lead to cell death.
In a healthy brain, cells called microglia break down the beta-amyloid. But when microglia become inflamed, which can be caused by alcohol consumption, they don’t perform the cleaning process, known as phagocytosis, as well as they do normally.
When the microglial cells of rats were exposed to alcohol for about the time that human cells would be exposed in heavy drinkers or binge drinking, their ability to clean beta-amyloid fell by 15 percent after just one hour.
“While these studies were performed in isolated cells, our results suggest that alcohol impedes the ability of microglia to keep the brain clear of amyloid beta and may contribute to the development of Alzheimer’s disease,” said Douglas Feinstein, Ph.D., professor of anesthesiology in the University of Illinois at Chicago College of Medicine.
Research on alcohol and Alzheimer’s is notoriously conflicting; some studies find that drinking moderate amounts is linked to a lower risk of dementia, but other studies have found that those same amounts were linked to a smaller hippocampus, the part of the brain that controls memory. What’s important to note about most studies on alcohol and cognition is that they’re observational, rather than a randomized controlled trial. That means that researchers are simply drawing associations between one factor of a person’s life and whether or not they developed dementia—but we can’t currently trace dementia to any one cause. It could be that other factors in someone’s life contribute to their dementia, rather than their drinking habits.
That being said, no study has ever found that excessive drinking—over three drinks per day for women and four for men—to be protective for brain health.
This study was published in the Journal of Neuroinflammation.