Cardiovascular disease and mental illness are among the top contributors to death and disability in the United States. At first glance, these health conditions seem to lie at opposite ends of the medical spectrum: Treating the heart is often associated with lab draws, imaging and invasive procedures, whereas treating the mind conjures up notions of talk therapy and subjective checklists.

Yet researchers are discovering some surprising ties between cardiac health and mental health. These connections have profound implications for patient care, and doctors are paying attention.

Depression has become recognized as a major issue for people with heart disease. Studies have found that between 17 and 44 percent of patients with coronary artery disease also have major depression. According to the American Heart Association, people hospitalized for a heart attack are roughly three times as likely as the general population to experience depression. As many as 40 percent of patients undergoing coronary artery bypass surgery suffer from depression.

Decades of research suggest these illnesses may actually cause one another. For example, patients with heart disease are often sick and under stressful circumstances, which can foster depressive symptoms. But depression itself is also a risk factor for developing heart disease. Researchers aren’t sure why, but something about being depressed — possibly a mix of factors including inflammatory changes and behavior changes — appears to increase risk of heart disease.

Depressed patients with cardiac disease have mortality rates twice as high as their non-depressed counterparts. Heart disease patients with depression are at higher risk of cardiac arrest, complications from surgery and hospital readmission after undergoing procedures than those without depression.

The issue has become so prominent that the American Heart Association and the American Psychiatric Association have recommended routine screening of heart disease patients for depressive symptoms.

And depression isn’t the only mental health issue related to heart disease. Researchers are discovering similar links between cardiovascular disease and other mental health conditions such as anxiety, bipolar disorder and schizophrenia.

Historically, caring for patients with both heart disease and mental illness has been quite difficult, as the treatment for one might worsen the other. For example, putting a patient through the stresses of a cardiac catheterization might worsen anxiety, depression or other psychiatric symptoms. Beta blockers, a key class of medications used to treat heart disease, were once thought to cause or worsen depression, though a 2002 review of studies found this claim “is not supported by data from clinical trials.” Meanwhile, older psychiatric drugs, such as tricyclic antidepressants, came with high-risk side effects on the heart.

Today, better awareness of the overlap between heart health and mental health is changing the treatment of these illnesses. More routine screening for depression and other mental health issues can help identify cardiac patients in need of collaborative care. Large-scale studies on the management of these diseases are helping clinicians choose treatments and medications more wisely.

New findings point to treatments that can be beneficial for the heart and the mind. Some evidence suggests newer generations of psychiatric drugs, such as selective serotonin-reuptake inhibitors, may protect cardiovascular health, and researchers are exploring whether cardiac medications such as anti-cholesterol statins could be used to treat mood as well. Health-care providers are also promoting preventive measures, such as exercise and stress management, that are known to enhance both cardiac health and mental health.

Despite these advances, the comorbidity of heart disease and mental illness continues to affect patient care every day. For example, as part of my medical training, I’ve worked on psychiatric consultation services in a number of hospitals, evaluating patients on medical or surgical floors who develop mental health needs. It’s not uncommon to be called to cardiac units, where patients experience distress ranging from depressed mood to acute suicidality.

I’ve chatted with patients about the crippling demands that heart transplants or bypass surgeries place on them. I’ve listened as patients struggle to speak, breathing heavily, lungs filled with fluid from congestive heart failure. Some patients fall into despair after years of endless medications, hospitalizations and poor health. Others are petrified by the operating room and the long road to recovery that lies ahead.

Sitting with these patients, I know mental health care can do only so much. Antidepressants won’t unclog their coronary arteries. Talk therapy can’t remove that fluid backing up into their lungs.

But by working together with our colleagues from other specialties, by helping the patient through the terrifying uncertainties of medicine, I hope we can do some good. A healthy mind won’t ensure a healthy heart. But, indeed, it helps.

Morris is a resident physician in psychiatry at the Stanford University School of Medicine.