When Illness Triggers Depression | When Depression Leads to Illness | The Diagnosis Dilemma | Depression's Devastating Effects | Treatment for Depression | Symptoms of Depression

Which comes first—depression or chronic illness? While the connection works both ways, one thing's for sure: treatment can make a difference.

Jennifer was 26 years old when her doctor diagnosed her with high blood pressure. But it wasn't until she learned that she also suffered from polycystic ovary syndrome that she began her slide into depression. Like many other patients with chronic illnesses, she hid her depression from her doctor, even as she underwent fertility treatments and a high-risk pregnancy.

"It's so hard to deal with a chronic illness," says Jennifer, now 29. "Many people are afraid to admit that they need help."

After the birth of her son, she broke down and told her doctor of her depressive symptoms—her self-imposed isolation from others, withdrawal from relationships, sleeplessness, and feelings of hopelessness. He helped her understand that like her other chronic conditions, her depression was not her fault. She began taking an antidepressant, and her outlook improved.

"It has helped tremendously," she explains. "I needed it to keep things in perspective for me, which it did."

When Depression Leads to Illness

In cases like Jennifer's, it's pretty clear that the illness led to depression. But for scores of other patients with conditions like heart disease and diabetes, the connection can be the reverse.

People with a history of depression are at least three times more likely to suffer from heart attacks than their non-depressed peers, according to William Eaton, PhD, professor of mental hygiene at the Johns Hopkins School of Hygiene and Public Health. "That ranks depression in the same strength as a risk factor as high cholesterol or family history of heart disease," he says.

Depression is also associated with type 2 diabetes, Dr. Eaton explains, adding that the links between depression and these illnesses likely work on different levels. "It could be behavioral—depressed people eat differently or exercise differently," says Dr. Eaton. "But it's also possible that it may work under the skin. In a person who is depressed, the blood clots differently, the immune system works differently, the heart beats with a different variation."