How harmful is a glass of wine a day?

A study published in the scientific journal Nature in March seems to offer some of the most compelling evidence that even moderate alcohol consumption can damage the brain.

After examining brain scans of more than 36,000 middle-aged and elderly people from Biobank in the UK, researchers found that 50-year-olds who drank an average of 175 milliliters (6 oz) or half-liter beer cans in days over the past year had brains that looked 1.5 years older than that of other people who drank half that amount or did not drink at all.

Brain aging increased with alcohol consumption, the researchers write. The study is one of the largest to address the health impact of moderate drinking on the brain to date. The researchers defined “moderate drinking” as up to 14 drinks per week and “light” as more than one drink per week, but less than seven. But many questions remain open.

Brain study

Although the results of the brain study seem straightforward at first glance, a little deeper research reveals how much we still do not know.

Patricia Molina, who heads the Center for Excellence in Alcohol and Drug Abuse at Louisiana State University, said it remained unclear what were the effects of the two-year-old brain contraction that caused the symptoms of aging in cognition and behavior.

Some evidence shows a link between loss of brain volume and impaired cognition, she said. But she is also unaware of any study that conclusively shows a direct link between specific percentages of reduced brain volume and clinical manifestations that are apparent to humans or their physicians.

Molina said the study form also made it difficult to answer questions about how its results compare to contraction caused by activities and other diseases known to cause a decrease in brain matter, such as physical inability or Huntington’s disease. . “A meta-analysis would be the closest way to the answer,” Molina said. In other words, one would have to look at the whole literature and analyze the results in a way that would allow such comparisons to be made.

Another reason why such comparisons are difficult to trace, Molina said, is that different activities or diseases cause different contractions in different places. Staying all day and eating only processed foods, for example, can cause contractions in an area of ​​the brain different from Huntington’s disease.

Then there is the chicken-egg dilemma. Could it be that people prone to drinking alcohol regularly simply have smaller brains in general than those who choose to abstain? “This is a special opportunity,” Molina said. “The only way to answer this question is to collect brain images from early life.”

Researchers are seeking to address this question through the study of adolescent brain cognitive development, Molina said. This study tracks changes in brain volumes over time while collecting data on alcohol and drug use.

But is not red wine good for you?

Evidence that excessive drinking is harmful to the body and brain is conclusive. But when it comes to moderate drinking, things get a little more complicated. A number of studies published over the past few decades, including one presented just a day before the brain study, seem to claim that moderate alcohol consumption may be good for you.

Analyzing data also obtained through the Biobank in the UK from around 312,000 current consumers, the researchers found that consuming the equivalent of approximately 150ml of wine alcohol per day for women and 300ml for men was associated with a lower risk of developing type 2 diabetes.

Jeanette Tetrault, a medical professor at Yale who specializes in alcohol addiction, said it was important to read beyond the headlines.

After all, she said, the study simply found that if you drank alcohol with food, you were less likely to develop type 2 diabetes than if you drank alcohol without food.

Critics of such studies also say that they often do not take into account important socio-economic factors and that the advertising of red wine benefits is essentially one-sided. This is because people with higher socioeconomic status, who are often already healthier, at first, are more likely to report drinking a glass of red wine a day than those who are not.

Be careful

A 2018 New York Times investigation found that researchers involved in a 10-year large-scale study seeking to track the impact of moderate alcohol consumption on health were heavily lobbied by the alcohol industry.

The $ 100 million used to fund the National Institutes of Health (NIH) study was sought primarily from key players in the alcohol industry, including Anheuser-Busch InBev. Its lead author, a Harvard medical professor, assured alcohol executives in emails and conference calls that the results would be in their favor.

When NIH investigators noticed suspicious practices, the study was discontinued. Although nothing ended up being published, the situation brings to your attention to take care of results that look too good to be true.

So how much care should I take?

A large 2018 study tried to resolve the debate over moderate alcohol consumption: No level of alcohol consumption improves health, he said.

Using data from 195 countries over a 26-year period, the study provided the most complete assessment of the global alcohol burden to date. But some scientists have pointed out flaws in the design of the study. For example, that instead of tracking their results in numbers, the authors tracked the results using relative language. When they offered tough figures, the level of damage seemed negotiable at best.

The risk of developing an alcohol-related health problem was 0.5% higher in people who drank one drink a day compared to those who did not. Numerically, the study found that 914 per 100,000 people between the ages of 15 and 95 would develop an illness within a year if they did not drink. That number increased by just four people, 918 to 100,000, if they drank.

Given what we know today about alcohol consumption, Tetrault said she was not telling her patients to abstain altogether. She said she can use brain study with patients who already have basic conditions that affect their cognition or their brain function as another tool for counseling.

“But I would not necessarily use this data to try to change the behaviors of patients who do not really have health consequences and to know what their potential risks are,” she said. “I’m not telling all my patients that they should abstain.”

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