Physical Activity May Lower Heart Disease Risk by 23%, According to a New Study

Many things with your health are tied together. For example, engaging in regular exercise can help lower your risk of heart disease and improve your mental health, including decreasing the risk of depression. Physical activity has also been shown to be beneficial for those undergoing treatment for depression. But lacking physical activity may have the opposite effect by increasing your risk for chronic diseases, including heart disease and depression. 

There’s also a link between depression and heart disease. According to the Centers for Disease Control and Prevention, those with depression and anxiety are at higher risk for heart disease. And the relationship is bidirectional, as having heart disease can also increase one’s risk for depression.

And while there may be several reasons for these relationships, a new study published in the Journal of the American College of Cardiology may have found another one. 

How Was the Study Conducted?

Because physical activity has been shown to reduce the risk of heart disease, stress and depression, researchers at Boston’s Mass General Brigham wanted to explore whether the reduction in heart disease risk from physical activity was in part from its stress-lowering effects on the brain. 

They used information from the Mass General Brigham Biobank, which is connected to patients’ medical records, all of whom had consented to the use of their information for research purposes. A total of 50,359 adults with an average age of 60, about 40% of them male, were used in this study. Researchers used information spanning 10 years. 

Besides some common demographical data—like age, sex, income, location, weight, BMI and lifestyle factors—researchers also looked at medical records regarding diagnoses of cardiovascular disease and depression. Physical activity records were also included. 

In addition, a subset of 774 participants provided brain images so that researchers could see activity in two specific areas of the brain—the amygdala and the ventromedial prefrontal cortex (VPC). 

The amygdala is a part of the brain that controls the fight-or-flight response. When this part of the brain senses fear or danger—even when it’s imagined—it sends signals to other parts of the body to get ready to react. This can cause stress and anxiety. 

On the other hand, the VPC is one of the decision-making areas of the brain. It processes emotions and uses reasoning to help control emotional reactions, as opposed to the amygdala which simply reacts to emotions. 

So for those who have depression or anxiety, the amygdala may be more active and the VPC less active compared to people who don’t have depression and anxiety. All of this brain activity shows up on brain scans—hence, why brain scans were also done for this study.

What Did the Study Show?

Researchers found that individuals who met the recommended levels of physical activity according to the 2018 Physical Activity Guidelines for America—150 minutes of moderate or 75 minutes of vigorous activity per week, plus at least two strength-training sessions—had lower amygdala activity. This remained constant even after adjusting for various factors. 

They also found a dose-dependent reduction in amygdala activity linked with physical activity. In other words, the more someone exercised, the calmer the amygdala tended to be. 

In addition to the amygdala being quieter in the people who exercised, the VPC was more active. This means that the exercisers were more likely to reason through emotions and have fewer emotional reactions—and less stress—compared to those who were not regular exercisers. 

“The decreases in stress-related neural activity were driven more by gains in cortical activity than by reductions in amygdalar activity,” notes lead study author, Amed Tawakol, M.D. 

Perhaps the least surprising finding was that those who met the minimal recommendations for physical activity had a 23% lower rate of heart disease (since other studies have shown this over time, per the CDC). Added to this, though, was that greater amygdala activity was also associated with a higher risk of heart disease. 

Specifically, greater amygdala activity—which, remember, means higher stress levels—was linked to higher risk factors for heart disease, including measures of calcium deposits in the coronary artery and markers of inflammation. Physical activity was inversely associated with these measures—meaning they tended to be lower in more active people. 

Researchers also found that those with depression at the beginning of the 10-year study period had higher activity in the amygdala but that this was brought down over the 10 years in those who met the physical activity recommendations. 

That’s not all that was brought down. They also found that for those with depression who exercised, the risk of heart disease was reduced by twice as much compared to those who did not have depression. Plus, this benefit continued to increase the more exercise they performed.

Ultimately, these findings led the researchers to conclude that physical activity may help reduce the risk of heart disease, in part, by moderating the stress reactions in the brain. 

The Bottom Line

Whether you have depression or not, engaging in at least the minimal amount of recommended physical activity a week may help reduce your risk of heart disease. If you do have depression, exercise may help improve your condition, in addition to reducing heart disease risk. According to this study, this may be due to exercise calming the emotional part of your brain and firing up the part of your brain that uses reasoning to process your emotions. Altogether, this reduces stress and the stress response, which ultimately reduces factors associated with heart disease and depression.