Small amounts of alcohol reduce stress on the brain and benefit the heart

One group of researchers says it can be explained why drinking small amounts of alcohol benefits the heart and how its main effect stems not from changes in the blood – as scientists initially believed – but from its repercussions on the brain.

However, because alcohol also increases the risk of cancer no matter how much is ingested, the researchers clarify that they do not advise people to consume it. Rather, understanding this mechanism may point to healthier ways to reap the same benefit, such as exercise or meditation.

For decades, large epidemiological studies have shown that people who consume moderate amounts of alcohol — less than one drink a day for women and one to two drinks a day for men — have a lower risk of serious cardiovascular events, such as heart attacks and stroke. (CVA), in comparison with people who abstain from alcohol and in relation to those who drink more.

However, scientists have never been able to figure out exactly why this occurs. Alcohol appears to increase levels of the “good” cholesterol known as HDL, and drinkers have lower levels of a sticky protein called fibrinogen in their blood, which can reduce the risk of dangerous clots. Also, in small amounts, alcohol can increase insulin sensitivity. But that doesn’t seem to fully explain the benefit.

So a team of cardiologists in Boston decided to look elsewhere for clues: in the brain.

The Doctor. Ahmed Tawakol, lead author of the study and co-director of the Massachusetts General Hospital Cardiovascular Imaging Research Center, noted that after drinking a little alcohol, before you feel the “buzz”, there is a feeling of relaxation.

“If you think about alcohol in the short term, the first effect that occurs is a somewhat de-stressing response,” he said.

For the study, Tawakol and his team analyzed the drinking habits of thousands of people enrolled in the Mass General Brigham Biobank. They found that those who drank between one and 14 drinks a week were less likely to have a heart attack or stroke than those who drank less than one drink a week, even after adjusting for genetics, lifestyle factors and other conditions. of risk.

They also analyzed brain scans of hundreds of these people and found that light or moderate drinkers had fewer stress responses in the amygdala, the part of the brain that processes fear and threats, as well as fewer heart attacks and strokes.

“We found that brain changes in light to moderate drinkers accounted for a significant portion of the cardiac protective effects,” said Tawakol.

The benefits were especially prevalent among people with a history of anxiety.

“Alcohol was twice as effective in reducing serious adverse cardiac events among people with stress and anxiety,” said Tawakol. “It was 20% in most patients, but a 40% relative risk reduction among individuals with prior anxiety.”

Tawakol studies the so-called stress neural network, centered in the part of the brain known as the amygdala. When the amygdala becomes overexcited, it activates the sympathetic nervous system, preparing the body for a fight-or-flight response. This causes blood pressure and inflammation to increase. Certain neurons also fire in the process, commanding the bone marrow to release more pro-inflammatory cells.

The endocrine system kicks in and pumps out cortisol, which tells the body to store fat, increasing the risk of diabetes and high blood pressure. It also secretes adrenaline and further increases blood pressure. Over time, this cascade of effects can increase the risk of heart attacks and strokes.

According to Tawakol, brain scans of light drinkers showed much less amygdala activity than non-drinkers and heavy drinkers, even though they had fasted before the scans, so they had no alcohol in their systems.

However, researchers have found that any amount of alcohol increases the risk of cancer, so finding alternative methods of reducing stress is important.

“With the same amount of alcohol that was ‘protective’ of cardiovascular disease, we saw a similar increase in cancer risk, so we’re not suggesting that there’s an attractive amount of alcohol to improve health,” said Tawakol.

Two good candidates for replacing light alcohol consumption to reduce stress are meditation and exercise, he said. One day there may also be a pill that reduces the effects of stress on the body.

“There are many studies on meditation, and meditation has an absolute impact on stress neural network systems,” he explained. Studies are looking at whether meditation sufficiently reduces the secondary components and, in turn, reduces the risk of heart attacks and strokes.

“Exercise has well-known effects on the brain, but in particular it has a very good dose-related effect on the stress neural network,” he said.

Some experts not involved in the study criticized its methods and message.

“This complex investigation is trying to find out why moderate alcohol use might be associated with a lower risk of heart attack,” said Naveed Sattar, professor of metabolic medicine at the University of Glasgow.

“The point is, we know that any amount of alcohol is associated with more strokes and heart failure, and with increased cancer and cardiovascular deaths,” Sattar said in a note.

“So focusing on just one small aspect, even if it’s true, gives the wrong impression and the title of better heart health with light to moderate alcohol is misleading and perpetuates old myths that we really need to get out of,” he insisted.

Petra Meier, professor of public health at the University of Glasgow, noted that the study can only show associations. She cannot prove that alcohol was the reason light drinkers seemed to have less stress in their brains.

“There are several explanations, including that light or moderate drinkers are different from non-drinkers in a number of personal characteristics. These differences explain why light alcohol consumption appears to be associated with beneficial health outcomes, but no alcohol consumption is the causative factor,” Meier said in a note.