For the study, the researchers analyzed data on more than 160,000 participants in 21 different studies from the Emerging Risk Factors Collaboration database and more than 400,000 participants from the UK Biobank database. Participants eligible for the new study had no history of cardiovascular disease at baseline.
After adjusting for age, sex, smoking status and history of diabetes, the study authors found that depressive symptoms — even at levels lower than what would be considered clinical depression — were associated with risks of cardiovascular disease, including coronary heart disease and stroke. However, the study authors note that the “magnitude of the association was modest.” (Yahoo Life reached out to the study authors, but they were not available for a timely response.)
“This study highlights the mind-body connection,” Dr. Laxmi Mehta, a cardiologist and director of Preventative Cardiology and Women’s Cardiovascular Health at the Ohio State University Wexner Medical Center, tells Yahoo Life. “It was interesting that even mild depression is associated with heart disease risks. What remains unclear is whether treatment of depression can positively impact heart outcomes, including treatment of mild depression.”
This isn’t the first study to find a link between depressive symptoms and cardiovascular disease. A December 2019 JAMA study on middle-aged and older Chinese adults found that depressive symptoms — in particular, restless sleep and loneliness — were “significantly” associated with a higher risk of cardiovascular disease.
The relationship between depression and heart health
There may be several factors that link depression and cardiovascular disease. Although the causes of depression are complex, research shows that stress is associated with the “onset of depressive episodes.” Dr. Asim Shah, professor and executive vice chair of psychiatry and behavioral sciences at Baylor College of Medicine, tells Yahoo Life that stress can also cause heart disease because “it increases blood pressure,” as well as cholesterol levels. Unmanaged stress can also cause heart rhythm disorders, says Shah.
Dr. Karly Murphy, an assistant professor of medicine at Johns Hopkins Medicine, tells Yahoo Life that people with depression experience fluctuations in cortisol levels — known as the primary stress hormone — which are also linked with cardiovascular disease. “That may also be contributory,” Murphy says.
In addition, there is research that shows depression and inflammation are “closely connected.” Inflammation also plays a role in heart disease and stroke. “All of these things go together,” says Shah.
According to Harvard University’s Harvard Heart Letter, depression has been linked to “low-grade inflammation, which is involved in the clogging of arteries and the rupture of cholesterol-filled plaque,” according to the university. “Depression also boosts the production of stress hormones, which dull the response of the heart and arteries to demands for increased blood flow. It activates blood cell fragments known as platelets, making them more likely to clump and form clots in the bloodstream.”
Mehta adds that depression may be related to “poor self-health and compliance with treatment, and in turn, higher rates of cardiovascular disease risk factors — i.e. diabetes, high blood pressure, lack of exercise, poor diet, smoking. In this study, depressive symptoms correlated with several cardiovascular disease risk factors. But even after controlling for some of the risk factors, there still was an association between depression and cardiovascular disease.”
“Mental health is just as important as physical health”
Shah says more comprehensive clinical research, with a “more structured” questionnaire to assess depression, is needed. But, he says, “we know from other studies there is an effect,” adding, “People with depression will have a higher risk of heart problems.”
Murphy points out that “you don’t have to be clinically depressed for it to maybe have some effect down the road on your heart health.” She says, “If I know that a patient is already struggling [with depressive symptoms] and they have risk factors for cardiovascular disease, I’m going to be even more in tune with how their mood impacts their ability to manage their risk factors.”
As Mehta puts it: “Mental health is just as important as physical health.”
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