A new study suggests that drinking any amount of alcohol may increase the risk of dementia, overturning the long-held belief that light or moderate drinking could protect the brain.
Researchers combined observational and genetic data from more than 3 million people, making this the most comprehensive look yet at alcohol and dementia. The findings, published in BMJ Evidence Based Medicine, show that risk rises in step with alcohol intake and no level of drinking appeared beneficial.
Past studies hinted that a glass of wine or two might lower dementia risk, but researchers say that may have been an illusion caused by “reverse causation.” People often drink less as their memory declines in the years before a dementia diagnosis, which could make light drinking look protective in older adults.
In this new study, observational data from over half a million participants in the U.S. and U.K. were paired with genetic analyses (Mendelian randomization) involving 2.4 million people. Both approaches pointed to the same conclusion: more alcohol, higher dementia risk.
For example, an extra one to three drinks per week was tied to a 15% higher risk of dementia. A doubling of genetic risk for alcohol dependency raised dementia risk by 16%.
“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.
The researchers note that while the strongest results were found in people of European ancestry, the overall message is clear: alcohol is not a safeguard for the brain, and reducing consumption may be an important strategy for dementia prevention.
This research used data from the Million Veteran Program and was supported by the Department of Veterans Affairs Office of Research and Development. It was also supported by the Wellcome Trust, the UKRI Medical Research Council and the NIHR Cambridge Biomedical Research Centre.