Many people living with pain cope with depression. I've read the pain can cause a change in body chemistry. What comes first, the chicken or the egg? Physical or emotional pain? What pattern of treatment seems to be most effective?
-Patricia, Virginia Beach, VA

It is estimated that more than half of all patients with chronic pain also have clinical depression. On the chemical level, these ailments are closely inter-related, and they might even be seen as two sides of the same coin.

There is a lot of research these days looking at the "HPA axis," a group of glands that helps our bodies react to physical stress and external danger. Stress causes these glands to pump out hormones such as cortisol (steroid hormone) and adrenaline (fight-or-flight hormone). When stress becomes chronic, as it does in the physical stress of chronic pain, the constant flow of these hormones causes depletion of the brain's reserves of two important chemicals, serotonin and norepinephrine. Low levels of these brain chemicals can cause depression.
Additionally, the low levels of serotonin and norepinephrine that are found in depression change the way the brain senses pain. Normally, these brain chemicals decrease the intensity of pain. When they are in short supply, the brain might interpret mild pain as being severe, and could even sense pain that has no external cause!

So chronic pain can cause depression, and depression can increase the intensity of pain. The HPA axis glands seem to be a link in this vicious cycle of events. Dysfunction of these glands may be a factor in fibromyalgia, an illness causing abnormal pain sensation and emotional distress.

Understanding that depression and pain are linked can help you cope with both. Strategies to reduce stress, proper sleep habits, and serotonin-boosting medications should help.

Amy Fogelstrom Chai, MD, MS, is an Internal Medicine Specialist with additional training in the area of medical research methods. Her experiences as a patient helped to redirect her priorities to home life and Christian ministry.