Exercise changes the brain in a way that helps heart health, especially for people with depression

By Madeline Holcombe, CNN

(CNN) — It’s common knowledge that exercise is good for your mental health and your heart health — and now a new study suggests that all three are working together.

In addition to the physical benefits of exercise, it’s also associated with a reduction in stress signals in the brain, which leads to a decreased risk of cardiovascular disease, according to the study.

Researchers analyzed data of more than 50,000 adults around age 60 from the Mass General Brigham Biobank, according to the study published Monday in the Journal of the American College of Cardiology.

The study looked at a survey that participants were given about their physical activity, imaging of their brains to track activity related to stress, and digital records of cardiovascular events.

“Individuals who exercise more had a graded reduction in stress related signals in the brain,” said lead study author Dr. Ahmed Tawakol, a cardiologist at Mass General Hospital and associate professor of medicine at Harvard Medical School in Boston.

“We found nice associations that exercise appeared to, in part, reduce heart disease risks by decreasing stress-related signals,” he added.

Everyone should pay attention whenever studies come out that show this kind of improvement resulting from a change in lifestyle, said Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver. Freeman was not involved in this study.

“These are incredibly cost effective, the magnitude of improvements are amazing — often better than many medications — and we should be putting these tools in our arsenal for ready use,” he said.

Twofold for people with depression

Tawakol and his team also wanted to know whether people with more stress-related signals in the brain would get a greater benefit from exercise, he said.

“Surprisingly, we additionally found a greater than twofold increase in benefits of exercise among individuals who are depressed versus individuals who don’t have depression or don’t have a history of depression,” Tawakol said.

The relationship between amount of exercise and decrease in the level of cardiovascular risk also varied depending on whether a person had a history of depression, he added.

For people without any history of depression, the benefit of exercise on cardiovascular disease reduction plateaued after about 300 minutes of moderate physical activity a week. But for people with depression, the benefits continued with more time spent, Tawakol said.

These benefits are in addition to the psychological benefits researchers already know exercise provides, he added.

“We know depression is an important risk factor for heart disease and it is also one of the most common stress-related conditions,” said study coauthor Dr. Karmel Choi, clinical psychologist and assistant professor at Harvard Medical School and Massachusetts General Hospital.

“Even though some people may be more susceptible to stress and its health consequences, here we see they may also stand to benefit more from exercise and its stress-modulating effects. Which is encouraging,” she added in an email.

How it works

Exercise reduced stress signals and increased prefrontal cortical signals, Tawakol said.

“Both are attractive changes in the brain,” he said.

The prefrontal cortex is the part of the brain responsible for executive function, which are the cognitive processes that control behavior, Tawakol said.

And stress signals in the brain are associated with things like inflammation, higher sympathetic nervous system activity, higher blood pressure, and diseases that thicken or harden the arteries, he added.

In part, exercise appeared to reduce heart disease risks by reducing the stress signals, Tawakol said.

These findings are just associations, however. Because the researchers observed participants rather than conducting a randomized trial with a control group, they cannot say for sure that the exercise caused the reductions or what the mechanisms are that underlie it, he said.

What exercise will make a difference?

You don’t have to be a pro athlete to have a good exercise routine, and it can help to work your way up, Freeman said.

“It turns out human beings were designed to move and move a lot, and when we do — particularly when we are outside and amongst trees — there’s been data to suggest these all have very significant stress-relieving effects.”

Freeman recommends checking with your doctor first and trying to get to 30 minutes a day of breathless physical activity — and it doesn’t matter what that activity is.

“If you don’t enjoy walking or biking or swimming or whatever it is, don’t do it. But figure out a way to get a physical activity in that you truly enjoy,” he said.

Just make sure that it feels difficult for you whatever your fitness level may be, Freeman added. If you can talk in full sentences while exercising, it might be time to make it harder, he said.

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