Its exact cause is unknown but is believed to involve psychological, genetic, neurobiological and environmental factors.[10][11][12] There is evidence that environmental factors and certain genes increase the risk of developing fibromyalgia – these same genes are also associated with other functional somatic syndromes and major depressive disorder.[13] The central symptom of fibromyalgia, namely widespread pain, appears to result from neuro-chemical imbalances including activation of inflammatory pathways in the brain which results in abnormalities in pain processing.[14] The brains of fibromyalgia patients show functional and structural differences from those of healthy individuals, but it is unclear whether the brain anomalies cause fibromyalgia symptoms or are the product of an unknown underlying common cause. Some research suggests that these brain anomalies may be the result of childhood stress, or prolonged or severe stress.[8]
Fibromyalgia has been recognized as a diagnosable disorder by the USNational Institutes of Health and the American College of Rheumatology.[15][16] On the other hand, Dr. Frederick Wolfe, the researcher credited with its discovery, has stated he believes that it is "clearly" not a disease but instead a physical response to depression and stress.[17] Fibromyalgia, a central nervous system disorder, is described as a "central sensitization syndrome" caused by neurobiological abnormalities which act to produce physiological pain and cognitive impairments as well as neuro-psychological symptomatology.[1] Despite this, there is controversy as to the cause and nature of fibromyalgia, as well as how patients are described by those in the medical community.[14][18]
Fibromyalgia is estimated to affect 2–8% of the population,[19] with a female to male incidence ratio of approximately 9:1.[20] The term "fibromyalgia" derives from New Latin, fibro-, meaning "fibrous tissues", Greek myo-, "muscle", and Greek algos, "pain"; thus the term literally means "muscle and connective tissue pain".