October 1, 2025
Any amount of alcohol may be bad for the brain. And the more you drink, the higher your risk of developing Alzheimer’s disease or other forms of dementia.
Those are the findings of a new study that looked at alcohol consumption and dementia risk in a large group of older adults living in the United States and Britain, and combined it with an analysis of genetic traits linked to alcohol consumption. The results challenge earlier research suggesting that light drinking may help to protect the brain.
For the study, published in the journal BMJ Evidence-Based Medicine, researchers looked at more than 500,000 adults enrolled in two large and long-running studies: the US Million Veteran Program and the UK Biobank. They ranged in age from 56 to 72 at the start of the study period and were monitored in some cases for longer than a decade. Of the 559,559 participants in the study, 14,540 eventually developed Alzheimer’s disease or another form of dementia.
Participants filled out questionnaires about their typical drinking habits, including how often they drank alcohol and the number of drinks consumed on a typical day, week or month. They ranged from nondrinkers to light drinkers (less than six drinks a week) to heavy drinkers (more than 40 drinks a week) and those with alcohol use disorder.
The investigators also used a research method called Mendelian randomization, which is designed to identify the root causes of specific medical outcomes—in this case the development of dementia. By looking at hundreds of genetic variations tied to alcohol consumption in dozens of studies involving some 2.4 million individuals, the researchers were better able to distinguish how drinking might impact the brain, compared to other health or behavioral characteristics that may raise the risk of dementia.
When the researchers looked only at the observational data from the US Veteran and UK Biobank studies, the findings suggested that moderate drinking may provide some protection against dementia risk. Nondrinkers, for example, seemed to have a higher risk of developing dementia than light to moderate drinkers did.
But when the researchers included, through Mendelian randomization, the genetic data tied to alcohol use, which seeks to filter out other health characteristics that may contribute to dementia risk, they found that any consumption of alcohol appeared to be bad for the brain. For example, an extra one to three drinks a week was associated with a 15 percent higher risk of developing dementia. And the more someone drank, the higher their risk.
The researchers also found that people who developed dementia typically reduced their drinking in the years leading up to their diagnosis. That finding may explain why some earlier studies seemed to suggest that moderate drinking offers benefits for the brain. “The pattern of reduced alcohol use before dementia diagnosis observed in our study underscores the complexity of inferring causality from observational data, especially in aging populations,” the authors wrote.
“Our study findings support a detrimental effect of all types of alcohol consumption on dementia risk, with no evidence supporting the previously suggested protective effect of moderate drinking,” the authors concluded. “They suggest that reducing alcohol consumption may be an important strategy for dementia prevention.”
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Anya Topiwalal, Daniel F. Levey, Hang Zhou, et al: “Alcohol use and risk of dementia in diverse populations: evidence from cohort, case–control and Mendelian randomisation approaches.” BMJ Evidence-Based Medicine, September 23, 2025
