Physical activity lowers risk of developing heart disease partly by reducing brain activity that gets triggered because of stress, new research has found.
This brain activity linked to stress was also lower in people who were more physically active, the study published in the Journal of the American College of Cardiology found.
Researchers found that lowering of such stress-related brain activity were driven by "gains in function" in the prefrontal cortex -- the region that helps in decision-making and adopting goal-oriented behaviour -- and is known to restrain brain stress centres of the brain.
The team also found that the cardiovascular benefit of exercise was "substantially" higher among participants expected to experience more stress-related brain activity, such as those having depression.
"Physical activity was roughly twice as effective in lowering cardiovascular disease risk among those with depression. Effects on the brain's stress-related activity may explain this novel observation," said senior author Ahmed Tawakol, an investigator and cardiologist at Massachusetts General Hospital, Harvard Medical School, US.
For the study, the researchers analysed medical records of more than 50,000 participants who completed a survey on physical activity. The team used data from the Mass General Brigham Biobank, a research program designed to help understand how people's genes, lifestyle, and environment impact their health.
Of the 50,000 participants, more than 700 also underwent brain imaging tests and measurements of stress-related brain activity.
Over a typical follow-up period of 10 years, the researchers found that roughly 13 per cent of the participants developed cardiovascular disease.
The participants meeting the physical activity recommendations were found to have a 23 per cent lower risk of developing heart and related diseases compared with those not meeting these recommendations.
"Prospective studies are needed to identify potential mediators and to prove causality. In the meantime, clinicians could convey to patients that physical activity may have important brain effects, which may impart greater cardiovascular benefits among individuals with stress-related syndromes such as depression," said Tawakol.
