Updated on June 13, 2023.
Drinking heavily—or abstaining entirely—during one’s middle years are associated with an increased risk of developing dementia later in life, compared with drinking moderately.
In a study published in August 2018 in the medical journal BMJ, researchers tracked 9,087 people in England starting when they were 35 to 55 years old, assessing their drinking habits and incidence of dementia over an average of 23 years of follow-up.
The authors found that, compared with moderate drinking, drinking no alcohol and drinking heavily were both linked to dementia. Moderate drinking was defined as consuming between 1 and 14 units of alcohol per week. Each unit is equal to 8 grams of pure alcohol, which is about the amount contained in 3 ounces of wine or 6 ounces of beer. Heavy drinking meant imbibing more than 14 units per week, which translates into about six or seven pints of beer or glasses of wine.
For those drinking more than 14 units a week, an increase of 7 units of alcohol each week was associated with a 17 percent greater risk of dementia, and long-term alcohol consumption above 14 units a week increased the risk of dementia by 40 percent compared with long-term moderate consumption. In the study, long-term meant an average of 23 years. Those with a history of requiring hospital admission for alcohol-related disease had more than a 400 percent higher risk of dementia.
Recent research had similar findings: In 2023, JAMA Network Open published a study of nearly 4 million people in Korea. Researchers found that sustained heavy drinking (of about two to three drinks per day) was linked to an 8 percent greater chance of being diagnosed with dementia, compared to mild and moderate drinking.
Should you stop—or start—drinking?
The available evidence on the relationship between alcohol use and dementia is mixed, but some research suggests that moderate drinking is associated with a decreased risk of dementia. The authors of the BMJ study noted that they found no evidence that drinking between 1 and 14 units of alcohol per week increased risk of dementia.
That said, the study’s finding on people who do not drink “should not motivate people who do not drink to start drinking alcohol,” according to study co-author Séverine Sabia, PhD, an epidemiology researcher with the French health organization Inserm and the University College London. Sabia, in an email interview with Sharecare, cited “adverse effects of alcohol on mortality, cirrhosis of the liver, and cancer” as reasons not to start drinking in the hopes of staving off cognitive decline.
As for why abstinence and excessive drinking were linked to increased risk of dementia while moderate drinking was not, the researchers had some theories, and noted that the underlying mechanisms were probably different for the different groups.
“In terms of biology, people who drink in moderation tend to have lower levels of inflammation or higher levels of good cholesterol,” Sabia explained. “But these people also tend to be more healthy and socially engaged, and that might lead to lower risk of dementia.” It’s important to note that, as an observational study, the research was unable to establish a cause-and-effect relationship between drinking and dementia.
As for the way in which heavy alcohol intake appears to increase the risk of dementia, Sabia noted that it may involve nutritional deficiency as well as the toxic effects of ethanol on the brain, along with the health impacts contributed by the increased risks of diabetes, hypertension, and stroke that come from heavy drinking.
