Treat depression and chronic pain separately, U-M researchers say

The two conditions often go together but should not just be treated with antidepressants alone, study finds -


Depression often causes a duet of anguish among people already suffering from chronic pain. But the two conditions retain
their independence from one another, and this may explain why medications used to treat patients' depression might not help
them manage their pain, a new study says.


Researchers at the University of Michigan Health System and the University of Cologne, Germany, have used functional imaging
of the brain to determine that in patients with the chronic pain syndrome fibromyalgia, their level of depression has little
influence on the intensity of pain they experience. This could be one of the reasons that treating a patient's depression by
prescribing an antidepressant that has no analgesic (pain-killing) properties may have little or no impact on their pain.



The study, in the May issue of Arthritis & Rheumatism, 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 and professor of rheumatology at the U-M Medical School. "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. The study was conducted at the Georgetown University Medical Center before Clauw and several
colleagues moved to U-M.


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.















"We have seen that if you give antidepressants to the average patient with fibromyalgia, they'll come back a couple of months
later and say, 'My pain isn't any better, but I don't feel so sad about it,' " Clauw says. "Our research provides further
evidence that these pathways are quite independent."


While this study looked at fibromyalgia patients, it is possible that the results may apply to people who have other chronic
pain conditions, such as low-back pain, irritable bowel syndrome and vulvodynia, the researchers say.


The lead author of the study was Thorsten Giesecke, M.D., research fellow at the U-M Chronic Pain and Fatigue Research
Center. In addition to Clauw and Giesecke, other others were Richard H. Gracely, Ph.D.; David A. Williams, Ph.D.; and Michael
E. Geisser, Ph.D., all of the U-M Health System; and Frank W. Petzke, M.D., of the University of Cologne. Giesecke also is
affiliated with the University of Cologne.


The research was supported by the Department of the Army and the National Institutes of Health, including a grant from the
General Clinical Research Center Program of the National Center for Research Resources.


Clauw and his team at the U-M Chronic Pain and Fatigue Research Center also are working on studies of activity, exercise and
pain among people with all kinds of chronic-pain conditions. They have started a registry of people who would be willing to
take part in such studies, both those with chronic conditions and those without. For more information on the registry and the
studies underway at U-M, visit med.umich/painresearch or call 866-288-0046.


Reference: "The Relationship Between Depression, Clinical Pain, and Experimental Pain in a Chronic Pain Cohort," Arthritis &
Rheumatism, May 2005; 52:5; pp. 1577-1584.


Contact: Katie Gazella

kgazellaumich

734-764-2220

University of Michigan Health System

www2.med.umich/prmc/media/relarch.cfm