This could be one of the reasons that treating a patient's depression by prescribing an antidepressant that has no analgesic properties may have little or no impact on their pain. The study notes that doctors often lump together the two conditions when they treat patients experiencing both of them. Some 30 to 54 percent of people with chronic pain also have a major depressive disorder.
"There is an incorrect impression among many doctors that if you treat a patient's depression, it will make their pain better. Not so,” says Daniel J. Clauw, M.D., one of the authors of the paper. Clauw is director of the U-M Chronic Pain and Fatigue Research Center. "If someone has pain and depression, you have to treat both.”
The study involved 33 women and 20 men with fibromyalgia, a type of chronic pain that affects several million people, more often in women than in men, and typically involves tenderness to the touch, stiffness and fatigue. In addition to those 53 patients, another 42 healthy companion participants were involved in the study.
The testing included a measurement of pain experienced by subjects based on their tolerance of pressure applied to their left thumbnails using a hard rubber probe. Researchers also conducted interviews and had the subjects fill out questionnaires. Using functional MRI (fMRI) scans, researchers compared the subjects' magnitude of pain, experimental pain sensitivity and symptoms of depression.
Clauw and the other researchers found that in fibromyalgia patients, much less pressure was required to activate the neurons associated with acute pain in the brain's sensory domain than among the healthy controls.
Clauw says that some other clinical research has supported the idea that pain and depression should be treated independently from one another. This, however, is the first time it has been shown using fMRI brain scans.
MEDICA.de; Source: University of Michigan Health System