Treating physicians often link the two symptoms, but no direct association has been found, say researchers

There appears to be no direct association between depression, extreme sensitivity to pain stimulus and how pain is processed in the brain in fibromyalgia patients with and without a diagnosis of clinical depression, according to research presented in 2004 at the American College of Rheumatology Annual Scientific Meeting in Orlando, Florida.

"This study challenges the notion that psychiatric symptoms such as depression cause or influence the pain seen in fibromyalgia and other chronic pain conditions," said Thorsten Giesecke, MD, of the U-M Chronic Pain and Fatigue Research Program, and lead investigator in the study, "and instead suggests that depression is a separate and somewhat independent process."

It is well known that many people with chronic pain conditions such as fibromyalgia also develop depression. In some cases, physicians treating such patients first treat the depression, thinking that is the primary problem and is causing the pain. This study suggests that pain and depression are quite separate processes, and that patients who suffer from chronic pain and have depression do not process pain differently than those who do not have depression.

Using functional MRI scans to record brain activity, calibrated pressure stimuli sufficient to produce slightly intense pain were applied to the left thumb of 30 fibromyalgia patients. Researchers were unable to find any significant association between the level of depressive symptomatology and the intensity of activity in areas of the brain previously shown to be involved in pain processing. However, researchers did find a link between the severity of depressive symptoms and brain activity in two areas of the brain not believed to be involved in pain intensity coding. In addition, researchers compared brain activity patterns of a subgroup of seven fibromyalgia patients with concurrent major depression (rather than increased symptoms of common depression) to a subgroup of seven fibromyalgia patients without depression and to seven patients in a control group. The study did not show any difference in the degree of pressure pain sensitivity and patterns of pain-elicited brain activity between fibromyalgia patients with depression and fibromyalgia patients without depression.

The American College of Rheumatology is the professional organization for rheumatologists and health professionals who share a dedication to healing, preventing disability and curing arthritis and related rheumatic and musculoskeletal diseases.

For more information:

Chronic Pain and Fatigue Research
http://www.med.umich.edu/painresearch/

American College of Rheumatology
http://www.rheumatology.org

U-M Health Topics A-Z: Fibromyalgia
http://www.med.umich.edu/1libr/aha/aha_fibromya_crs.htm

Medicine at Michigan: The Pain of Fibromyalgia
http://www.medicineatmichigan.org/magazine/2002/
fall/huron/14huron.asp

U-M Depression Center
http://www.med.umich.edu/depression/

Understanding Depression
http://www.med.umich.edu/depression/understanding.htm