For people diagnosed with a physical condition or coping with chronic illness, depression can be a common complication. According to figures from the U.S. Centers for Disease Control and Prevention, nearly 50 percent of asthma patients suffer from depressive symptoms, one in six people who have had a heart attack have major depression, and people with diabetes are twice as likely to be depressed.

“Feeling sad or depressed about a chronic illness diagnosis is normal,” said Kristin Kuntz, PhD, an assistant professor of clinical psychiatry at Ohio State University. “It’s a normal reaction to the shock of diagnosis. But then you have to watch and see if the depressed mood persists, if they’re still having trouble eating and sleeping even after their medical illness is being treated.”

As John Lehrmann, MD, chairman of the psychiatry department at the Medical College of Wisconsin points out, pain associated with an illness can cause depression. “There’s no question that we understand pain is associated with increased risk of depression, and many chronic illnesses cause pain,” he said. However, even when a patient doesn’t have painful symptoms, “living with a chronic illness can affect your sense of who you are. It adds a level of stress to what you already have to live with each day.”

Depression often goes undiagnosed because it can share symptoms with the illness that triggered it, such as changes in sleeping and eating patterns or general fatigue. Fortunately, as Dr. Lehrmann noted, primary care practices are increasingly integrating mental health screening and treatment into their clinics. That could help more patients with depression get treatment sooner. “It’s especially important for doctors treating their chronic illness to be looking out for them and recommending treatment,” Lehrmann said.

A patient’s loved ones or caregiver can help spot early signs of depression. Experts agree that social withdrawal and loss of interest in hobbies or other activities are common indicators. Kuntz gives the example of someone with Parkinson’s disease, a chronic degenerative disease that affects movement. “If a person who has Parkinson’s used to like to take long walks and now they can’t do that because of the disease, they might lose interest in that activity altogether and just decide to stay in bed because they can’t do the things they used to do,” she said.

“If someone is not answering the phone, keeping to themselves and staying in bed more often, those are key things to look out for,” said Robin Kerner, PhD, director of quality initiatives and outcomes in the psychiatry department at St. Luke’s-Roosevelt Hospital Center in New York City.

Chronic illness and depression can become a vicious cycle. “The depression itself makes them less likely to get treatment, and on top of that they have this illness that’s making them feel weak and changing how they feel about themselves,” said Kuntz. “They’re dealing with a lot, and this is one more thing on their plate.”

Once a patient’s depression is diagnosed, there are several treatment options including counseling and medications. “If you initiate treatment, their quality of life and overall mood can greatly improve,” said Kerner.

Even with treatment, “people need to get used to a ‘new normal,’” said Kuntz. “There will be ups and downs. They may feel generally well one day and not be able to get out of bed the next day because of their illness. They’ll relate to others and their physical environment differently than usual.”