In a new study published in Nature Mental Health, researchers from Vanderbilt University Medical Center and Massachusetts General Hospital have discovered potential genetic links between coronary artery disease, major depression, and cardiomyopathy — a condition that affects the heart muscle. The findings suggest that these links are mediated by inflammatory pathways and that medications used for coronary artery disease and depression might, together, help reduce inflammation and the risk of developing cardiomyopathy.
Coronary artery disease is one of the most common types of heart disease and a leading cause of death worldwide. It occurs when the major blood vessels that supply the heart with blood, oxygen, and nutrients (coronary arteries) become damaged or diseased. Cholesterol-containing deposits (plaques) in the arteries and inflammation are usually to blame.
As these plaques build up, they narrow the arteries, decreasing blood flow to the heart. This can result in chest pain, shortness of breath, or other symptoms, and can lead to more serious complications like heart attacks.
Major depression, also known as major depressive disorder (MDD), is a serious mental health condition characterized by persistent feelings of sadness, hopelessness, and a lack of interest or pleasure in daily activities. It affects how a person feels, thinks, and handles daily activities. The condition is linked to a variety of emotional and physical problems and can decrease a person’s ability to function at work and at home.
Cardiomyopathy refers to diseases of the heart muscle. In cardiomyopathy, the heart muscle becomes enlarged, thick, or rigid, and in rare cases, the muscle tissue is replaced with scar tissue. As the condition worsens, the heart becomes weaker and is less able to pump blood throughout the body and maintain a normal electrical rhythm. This can lead to heart failure or irregular heartbeats called arrhythmias. Cardiomyopathy can be caused by a range of factors and conditions, including genetic and lifestyle factors.
Previous studies have established a significant overlap between coronary artery disease and major depression, with up to 44% of patients with coronary artery disease also suffering from major depression. Despite these associations, the underlying biological mechanisms connecting these conditions remained elusive.
Inflammation has been identified as a common factor in both conditions. Elevated levels of inflammatory markers are noted in patients suffering from depression and those with coronary artery disease, hinting at a shared biological pathway. This observation led researchers to further investigate whether a genetic basis underlies these connections.
The team employed transcriptome-wide association scans, a sophisticated technique that helps identify genetic variations that influence gene expression related to both major depression and coronary artery disease. The researchers identified 185 genes that were significantly associated with both coronary artery disease and major depression.
These genes were notably involved in biological processes related to inflammation. This overlap suggests that these conditions may share a common genetic predisposition that influences their development through inflammatory pathways.
“This work suggests that chronic low-level inflammation may be a significant contributor to both major depression and cardiovascular disease,” said the paper’s corresponding author, Lea Davis, an associate professor of Medicine in the Division of Genetic Medicine and Vanderbilt Genetics Institute.
The researchers explored the actual impact of these genetic findings in clinical settings by examining large electronic health records from Vanderbilt University Medical Center, Massachusetts General Hospital, and the National Institutes of Health’s All of Us Research Program. Interestingly, they found that the incidence of cardiomyopathy in patients who had genetic markers for both coronary artery disease and major depression was lower than expected, especially when compared to those with coronary artery disease alone.
This observation led the researchers to hypothesize that the standard treatments for coronary artery disease and major depression, such as statins and antidepressants, might have a protective effect against cardiomyopathy by reducing inflammation.
This hypothesis aligns with the idea that both coronary artery disease and major depression involve chronic inflammation, and managing this inflammation could be crucial in treating or preventing associated conditions like cardiomyopathy. It suggests a potential therapeutic synergy in treating these patients with a combination of cardiovascular and psychiatric care that could help in managing or even preventing the progression to cardiomyopathy.
While the study presents significant findings, the authors acknowledge several limitations. The reliance on electronic health records can introduce biases related to how diseases are recorded and managed in different settings. Additionally, the genetic analysis was predominantly based on data from individuals of European ancestry, which may not be generalizable to all populations.
The researchers advocate for more studies to explore the optimal treatment mechanisms and to confirm these findings across more diverse populations and settings. They also suggest that future research should continue to consider the intertwined nature of mental health and heart health, potentially leading to more comprehensive treatment strategies.
“More research is needed to investigate optimal treatment mechanisms,” Davis said, “but at a minimum this work suggests that patient heart and brain health should be considered together when developing management plans to treat major depression or cardiovascular disease.”
The study, “Genes associated with depression and coronary artery disease are enriched for cardiomyopathy and inflammatory phenotypes,” was authored by Kritika Singh, Hyunjoon Lee, Julia M. Sealock, Tyne Miller-Fleming, Peter Straub, Nancy J. Cox, Quinn S. Wells, Jordan W. Smoller, Emily C. Hodges, and Lea K. Davis.