Alcohol: Bad for Heart, Brain, and Cognition?

This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women’s Hospital. I’d like to talk with you about a recent report on alcohol consumption and the risk of dementia. It seems we’ve been misled about alcohol and health.

First, countless observational studies have suggested that alcohol protects the heart, the brain, and even leads to a longer lifespan. Then we were told the earlier studies may have produced spurious results because drinkers were compared to 1) nondrinkers who had often stopped drinking because of health problems, doctor’s advice, or being started on medications that interfere with alcohol consumption, and 2) moderate drinkers, who often tended to be of higher socioeconomic status and had healthier lifestyle practices.

When analyses were redone or new studies conducted, alcohol was linked to higher risks for hypertension, heart disease, stroke, atrial fibrillation, heart failure, and many other forms of cardiovascular disease — not to mention accidents, trauma, cirrhosis, several forms of cancer (eg, gastrointestinal and breast), and shortened lifespans.

Now, a new study that leveraged two large cohorts and a Mendelian randomization approach suggests that alcohol is also linked to an increased risk for dementia, with no safe level of drinking. The study, which was recently published in BMJ Evidence-Based Medicine, is fairly compelling. The investigators analyzed data from more than half a million participants in two large observational cohort studies: the UK Biobank and the US Million Veteran Program. The participants were aged 56-72 years at baseline and there were close to 15,000 incident cases of dementia.

In addition to seeing a higher risk for dementia with higher alcohol intake, a Mendelian randomization analysis that evaluated gene variants strongly related to alcohol consumption showed a monotonic increase in dementia risk with the genetic traits linked to alcohol intake. There was no evidence that moderate drinking protected against dementia.

The findings suggested that drinking any amount of alcohol seemed to increase dementia risk on a population level. The Mendelian randomization analysis suggested a causal role of alcohol consumption in increasing dementia risk with no evidence supporting protection, although the typical U-shaped curve was seen in the observational analyses. The researchers also found that people who developed dementia typically drink less in the years leading up to their diagnosis, suggesting reverse causation: Cognitive decline leading to reduced alcohol intake may underlie some of the protective associations seen with alcohol in observational studies.

These are important findings because in 2023, the World Health Organization issued a statement that no amount of alcohol is safe. Further, bench neuroscience research suggests that alcohol is directly toxic to neurons in the brain. So, it’s time to share this news with our patients and the public. We’ve been misled and mounting evidence challenges the notion that moderate alcohol consumption is protective of either the heart or brain. We should support our patients in reducing alcohol intake and certainly not encourage uptake of this habit for improving their health.