Individuals with depression often suffer from chronic physical pain and chronic pain sufferers are often depressed. A new study shows that both conditions should be tackled separately and independently from each other.

"There is a sense in clinical practice that if someone has both pain and depression, that maybe depression is causing the pain and if you address depression the pain will get better," Dr. Daniel J. Clauw from the University of Michigan in Ann Arbor stated. His group's findings contradict that theory.

Does depression bring about pain? Or does pain lead to depression? Because these two conditions frequently co-exist, there has been much speculation about whether one causes the other or whether a common underlying factor provokes both, Clauw and colleagues note in a report in the medical journal Arthritis and Rheumatism.

To investigate, they studied 53 patients with fibromyalgia, a condition characterized by widespread pain and tenderness to the touch, which is often accompanied by depression. They also studied 42 healthy controls.

Based on results of brain imaging studies and a thumbnail pressure test, the researchers found that fibromyalgia patients needed much less applied pressure to the thumbnail than healthy controls to activate neurons associated with acute pain. This heightened sensitivity to pain applied to fibromyalgia patients, regardless of whether or not they were depressed.

Additionally, according to the researchers, there was only a weak link between sensory regions of the brain associated with pain and emotional regions of the brain associated with depression.

While depression and pain often occur concurrently, that does not mean they're the same underlying problem and can be managed in the same way, Clauw said. Therefore, prescribing an antidepressant will not necessarily relieve the suffering of a depressed patient whose pain is not only real but also intensely physical, he and colleagues note.

SOURCE: Arthritis and Rheumatism May 2005.