Depression: The Power of Mood

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Heart disease is one of a long list of illnesses that worsen with depression. People with such afflictions as cancer, diabetes, epilepsy and osteoporosis all appear to run a higher risk of disability or premature death when they are clinically depressed. The effect is potentially so significant that the medical profession has begun to focus serious attention and resources on trying to understand what's going on. At a national conference in Washington in November, Evans served as co-chairman of a meeting, sponsored by the nonprofit Depression and Bipolar Support Alliance (DBSA), to get a better handle on how widespread the problem is. For two days, experts in cancer, AIDS, heart disease, diabetes and other diseases, along with patient advocates, listened to the evidence linking depression with one illness after another.

Fortunately, scientists have made great strides in sorting out the underlying causes of depression: it is almost certainly a defect in some combination of key genes, plus the right triggering environment. And researchers are well along in developing some promising therapies, pharmacological and otherwise, to supplement what is already available. But while the disease-depression connection is becoming more and more clear, how to uncouple them is an uncharted process. "You would think that treatment would alter the negative relationship between depression and other illness," says Dr. Dennis Charney, head of mood-and anxiety-disorders research at the National Institute of Mental Health (NIMH). But, he adds with proper scientific caution, "we don't have proof of that yet."

The idea that treating depression might lessen the severity of other diseases, though, makes basic biochemical sense. Everyday experience makes it clear that brain chemistry governs more than just the emotions. When your mind feels terror, the resulting surge of adrenaline makes your stomach churn. When your mind is sexually aroused, the body responds in unmistakable fashion. The effect is even more direct with the 60 or so chemicals known as neurotransmitters, which signal one cell that its neighbor has just sparked and that it should pass along the message. Brain chemicals such as serotonin circulate everywhere, not only in the brain. "Depression really is a systemic disorder," says Evans, "and many of the neurotransmitters that we believe are involved in the pathophysiology of depression have effects throughout the body."

Precisely how these powerful chemicals affect the course of heart disease, cancer and other illnesses isn't well understood yet, but preliminary research has yielded some tantalizing clues. When serotonin circulates in the bloodstream, for example, it appears to make platelets less sticky and thus less likely to clump together in artery-blocking blood clots. For years, heart-attack survivors have been advised to take a children's aspirin daily for clot prevention; such drugs as Prozac, which keep serotonin in circulation, seem to have a similar effect.