It’s well established that having a heart attack or stroke puts people at risk for developing depression, but research now points to a heart-mood relationship that goes both ways: One study found that people with depression had a 57% increased chance of heart attack or stroke. “In terms of its effect on the heart, depression may have almost as much of an impact as traditional risk factors like high blood pressure,” says Jesse Stewart, Ph.D., a professor of psychology at Indiana University-Purdue University Indianapolis.

Experts are still working to understand the relationship, but one major factor may be that people with depression often struggle to maintain healthy lifestyle habits like exercising, eating right, and taking prescribed medications on schedule, all of which have an effect on the heart. Inflammation—the immune system’s response to everything from injury to stress—is another likely player. Depression can heighten inflammation in the body, and chronic inflammation may lead to hardened blood vessels and plaque buildup in arteries, which can trigger a heart attack or stroke. This expanded understanding of how the two are connected underscores the importance of taking action. Here’s how, according to experts:

Be Alert for Symptoms

Depression is characterized by unshakable sadness, feelings of worthlessness, and a loss of interest in hobbies, work, or socializing. Loved ones may notice these changes before you do. You may also experience fatigue, anxiety, sleep trouble (either insomnia or oversleeping), and difficulty concentrating.

Seek Help

If you suspect that you’re suffering from depression, find a therapist (asking friends for a recommendation is a good start) or talk to your primary care doctor, who may recommend medication, can give supportive tips, and could know a therapist who would be a good fit.

Be Patient

Change doesn’t happen overnight—it can take time along with trial and error to find the right treatment plan. Be open to evidence-based talk therapies (like cognitive behavioral therapy) and antidepressant medication, both of which can make all the difference.