NEW YORK (Reuters Health) Dec 26 - Based on a review of published studies, there is now "overwhelming" evidence that fibromyalgia is real, report two researchers from the University of Michigan Medical School in the journal Current Pain and Headache Reports. "It is time for us to move past the rhetoric about whether these conditions are real, and take these patients seriously as we endeavor to learn more about the causes and most effective treatments for these disorders," write Drs. Richard E. Harris and Daniel J. Clauw. Fibromyalgia is characterized by a lower pain threshold and is associated with genetic factors, they note. It affects 2%-4% of the population, often causing debilitating pain, and is often misdiagnosed as arthritis or deemed psychogenic. The scientific literature, however, does not support this, Drs. Harris and Clauw point out. On the contrary, the data suggest that fibromyalgia and a number of overlapping pain syndromes are characterized in part by "augmented central nervous system processing of pain, as evidenced by hyperalgesia and/or allodynia on examination." "This phenomenon can occur in association with certain psychological factors (e.g. catastrophizing), but psychological factors are not in any way required for an individual to develop or maintain this augmented central pain state." Functional magnetic resonance imaging and single photon emission computed tomography studies have revealed differences between patients with and without fibromyalgia in central brain structures. In addition, researchers recently reported evidence suggesting that a genetic polymorphism of the COMT (catechol-O-methyl transferase) gene may explain variations in pain sensitivity. Mutations in COMT have also been linked to the development of temporomandibular joint pain. Additional support for the validity of fibromyalgia, Drs. Harris and Clauw note, comes from the beneficial effects on fibromyalgia pain achieved with drugs such as tricyclics and anticonvulsants that are known to increase anti-nociceptive influences. Current Pain Headache Rep 2006;10:403-407.