Many studies have suggested that light drinking can do the heart some good, and now researchers think they have found one reason why: It helps the brain relax.
It's no secret that many people pour a drink as a way to unwind and shed the stressors of the day. And research suggests that is not just a placebo effect. In the short term, alcohol has a quieting effect on the amygdala — a brain area that processes potential threats in our surroundings.
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Now the new study shows that amygdala activity is habitually dialed-down in moderate drinkers, relative to non-drinkers. And that appeared to partially account for their lower risks of cardiovascular ills, including heart attack and stroke.
The findings, published in the June 2023 issue of the Journal of the American College of Cardiology, add to a large body of evidence connecting moderate drinking to a lower heart disease risk.
"Moderate" is generally defined as no more than one alcoholic drink per day for women, and no more than two per day for men.
No one, however, is suggesting that people drink for the sake of their heart health, experts stressed.
For one, alcohol can clearly have harms. There's the potential for abuse and dependency, and heavy drinking is known to be detrimental — including to the brain. Even moderate drinking can carry health risks, including heightened odds of developing certain cancers.
"There is no 'safe' level of drinking," said senior researcher Dr. Ahmed Tawakol, co-director of Massachusetts General Hospital's Cardiovascular Imaging Research Center.
So alcohol, Tawakol said, is not where his research interest lies. Instead, he and his colleagues wanted to dig into the reasons why light-to-moderate drinking is tied to lower cardiovascular risks.
Then it might be possible to find other ways to mimic the benefits without the risks, he noted.
Tawakol's team started with data on more than 50,000 adults enrolled in a large health research project. They found, as many previous studies have, that people who were light-to-moderate drinkers had a lower risk of major cardiovascular "events" — including heart attacks and strokes.
Compared with non-drinkers, they were 22% less likely to suffer those problems over three years. That was after the researchers factored in other influences, such as people's smoking and exercise habits, medical conditions, education level and income.
Next, the researchers focused on a subset of 754 participants who had undergone PET/CT brain scans for medical reasons. They wanted to see whether those participants' self-reported drinking habits correlated with differences in the brain's stress signaling.
The answer was yes. On average, light-to-moderate drinkers showed reduced signaling in the amygdala, versus people who abstained or rarely drank.
That brain difference, the researchers found, explained part of the lower cardiovascular risks among lighter drinkers.
People do need an alert amygdala to have appropriate responses to threats from the environment. But when it's chronically overactive, the researchers explained, that can take a toll on the cardiovascular system — elevating blood pressure and feeding inflammation in the blood vessels, for example.
Nobody would recommend that people use alcohol to calm their amygdala, said Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver.
"The interesting thing about this study is that it points to the importance of stress reduction," said Freeman, who was not involved in the research. "Can you replicate [these findings] with something that doesn't have the harms of alcohol?"
Freeman said he suspects that is very possible -- through, say, mindfulness practices or physical exercise.
Tawakol suspects the same. In fact, he said, he and his colleagues are now studying the effects of physical exercise and mindfulness-based stress reduction.
For now, Tawakol said he hopes people can take away a couple basic messages: The "brain-heart connection" matters, and it's important to have healthy ways to manage life's stressors.
Freeman agreed, and said that people should go for the particular method that works best for them and is sustainable.
"Not everyone wants to meditate," Freeman said. "People have to find their own path."