Drugs traditionally used to treat depression are also effective in easing widespread pain, sleep disturbances and dismal moods associated with fibromyalgia syndrome (FMS), according to a large-scale analysis published today in JAMA The Journal of the American Medical Association. The study confirms earlier research about the meds' effect on symptoms associated with this mysterious disease.

Fibromyalgia, an often overlooked disorder believed to cause widespread muscle pain, sleep disturbances, depression and fatigue, affects up to 12 million people (4 percent of the U.S. population), nearly 11 million of them women. The degree of debilitation caused by the disease ranges "from very little to total," says Roland Staud, a professor of medicine at the University of Florida College of Medicine in Gainesville, adding that he has known some patients who have been bedridden for as long as a year because of symptoms, which typically appear between ages 40 and 60 and may last for the remainder of sufferers' lives.

Researchers do not know the cause of FMS and there is currently no cure. But psychiatrist Leslie Arnold, director of the Women's Health Research Program at the University of Cinncinnati's College of Medicine, says that both genetics and stress appear to play a role. Only two drugs have been approved by the U.S. Food and Drug Administration (FDA) to treat fibromyalgia—Cymbalta made by Eli Lilly (one of the antidepressants reviewed in this study) and Pfizer's Lyrica, an Rx to control seizures and pain. 

There is no definitive test for fibromyalgia, which doctors typically diagnose based on symptoms, including chronic widespread pain.

German researchers reviewed findings from 18 clinical trials (involving a total of 1,427 people in North America, South America and Europe) on the effect of antidepressants in relieving symptoms of fibromyalgia. Trial participants were given a drug from one of four classes of antidepressant drugs—tricyclic and tetracyclic antidepressants (TCA's), selective serotonin reuptake inhibitors (SSRI's), monoamine oxidase inhibitors (MAOI's), and serotonin and noradrenaline reuptake inhibitors (SNRI's).

"All classes of antidepressants had substantial effects on pain [but] we found differences between the classes of antidepressants on other key symptoms of FMS such as sleep disturbances, fatigue and depressed mood," says lead study author Winfried Häuser, an internist at Klinikum Saarbrücken, a hospital in Germany.

For example, SSRI's (such as Prozac) significantly reduced pain and lightened depression, but did not relieve fatigue or sleep disturbances, whereas SNRI's (such as Cymbalta) helped with pain, sleep disturbances and the blues, although they did not perk up the weary. TCA's (such as Vanatrip) helped alleviate pain, fatigue and sleep disturbances, but MAOI's (such as Manerix) only seemed to help with pain.

"This is a major advance," says Arnold. "We are trying to identify new treatments for fibromyalgia and raise awareness for this disease."

Rheumatologist Philip Mease, director of the rheumatology research division at the Swedish Medical Center in Seattle, is concerned that people will interpret these findings to support a common misconception that fibromyalgia is an offshoot of depression, and that treating that condition will make it go away.

"I am a crusader against the term 'antidepressant' because they [the drugs investigated in this study] are not used as antidepressants in this context," but rather to dull pain, Mease says.

Dan Clauw, an anesthesiologist at the University of Michigan at Ann Arbor, agrees. "The strong implication to the reader is that these people [in the study] are getting better because they are depressed," and being treated for that condition, he says. "There is pretty overwhelming evidence that these [drugs] are not [only] working as antidepressants [but as pain killers, as well]."