STUDY: Even Small Amounts of Alcohol Seem to Boost Dementia Risk

Evidence continues to emerge that a glass or two of wine, or other alcoholic drinks, does not have the heart and brain benefits once espoused. The latest research suggests that, to the contrary, even small amounts of alcohol increase dementia risk. 

This means that even light- to moderate- drinkers may be more at risk than previously thought. It’s even worse news for the 65 percent of adults over age 65 in the U.S. whose regular drinking habits exceed the daily guidelines of one drink for women and two for men.

The new study published in BMJ Evidence-Based Medicine examined more than half a million older adults across the US and UK. After controlling for many different variables, the researchers found that any amount of drinking increased dementia risk, with every drink adding more risk. Going from one to three drinks per week, for example, increased the risk by 15 percent. 

The study’s lead author Dr. Anya Topiwala, a psychiatrist and researcher at the University of Oxford, told Being Patient that “even small amounts of alcohol may increase dementia risk, and that moderate drinking is unlikely to be protective.”

Drinking in moderation is not protection

For years, researchers studying the relationship between alcohol and dementia found a U-shaped relationship. People who drank the least, and those who drank the most, were at the highest risk, while moderate drinkers appeared to show some protection. But many of these studies didn’t control for behavioral and genetic factors that might explain the relationship.

“We found that many studies exaggerate the benefits of moderate drinking due to methodological flaws,” University of Victoria researchers James Clay and Tim Stockwell wrote in The Conversation.

According to Topiwala, moderate drinkers tend to be “better educated, wealthier, and thus more generally healthy and score better in memory tests.” Without taking these factors into account, other studies falsely concluded that drinking, rather than these other behavioral and demographic factors, was protective, she said.

Going a step further, the researchers also examined genetic data from more than 2.4 million people. By using genetic data, the team could test whether alcohol itself, rather than lifestyle factors, directly causes dementia. They concluded that tripling the number of drinks — for instance, from one to three a week — increased dementia risk by 15 percent. Genes that are linked to alcohol use disorders also showed a strong connection. Having twice as many of these genes increased the risk by 16 percent.

Would controlling for these factors reveal a different relationship between alcohol and dementia risk? To find out, Topiwala and her colleagues analyzed data from a total of 559,559 people. The U.S. participants were followed for an average of four years, while U.K. participants were followed for about 13 years. Over this time period, 10,564 of them developed dementia. 

Most participants reduced their alcohol intake over time, but those who later developed dementia showed the steepest decline. 

Dr. Timothy Naimi, professor at the University of Victoria, who wasn’t involved in the research, told Being Patient that the data helps explain the flaws in previous observational studies. “Those who are developing dementia may stop drinking, making it appear falsely that not drinking or hardly drinking is a risk for dementia,” said Naimi. 

How does drinking damage the brain?

When you drink an alcoholic beverage, the ethanol is absorbed directly from the stomach into the blood vessels, reaching the brain in five minutes. From there, it only takes another five minutes for the alcohol to start affecting the brain. Alcohol disrupts the communication of neuronal signals within the brain, affecting your reaction speed, judgment, and thinking.

But it isn’t entirely clear how it leads to dementia. Topiwala explained that heavy drinkers develop a vitamin B1 deficiency that may drive the disease. Otherwise, she said that “alcohol may directly kill brain cells” and damage blood vessels.

Studies have found that cognitive function starts improving one year after you stop drinking. The parts of the brain that carry out important cognitive functions start to thicken and rebuild after seven months of abstinence. Across these studies, however, smokers don’t recover as well from alcohol-induced deficits as non-smokers. Reducing  drinking has other benefits too, including lowering cancer risk. 

 “The findings are strongly supportive of the notion that when it comes to dementia, the less alcohol consumption the better,” said Naimi.