Fibromyalgia - Causes

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Abnormal Pain Perception and Substance P. Some studies have suggested that fibromyalgia may involve too much activity in the parts of the central nervous system that process pain (the nociceptive system). Brain scans of fibromyalgia patients have suggested abnormalities in pain processing centers. Of particular interest is research that has detected up to three times the normal level of substance P in the cerebrospinal fluid of fibromyalgia patients. Substance P is a chemical messenger of the nervous system, and is associated with increased pain perception.

Some fibromyalgia patients may also be oversensitive to external stimulation, and overly anxious about the sensation of pain. This increase in awareness is called generalized hypervigilance. One study compared patients with fibromyalgia or rheumatoid arthritis to those without chronic pain. The different groups' responses to pain and noise were measured. Of the three groups, the fibromyalgia patients were least tolerant of and most attentive to such stimuli. However, a 2001 analysis of studies on fibromyalgia found no strong support for the hypervigilance theory.

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Immune Abnormalities

Fibromyalgia has some symptoms that resemble those of some rheumatic illnesses, including rheumatoid arthritis and lupus (systemic lupus erythematosus). These are autoimmune diseases in which a defective immune system mistakenly attacks the body's own healthy tissue, producing inflammation and damage. The pain in fibromyalgia, however, does not appear to be due to autoimmune factors, and there is little evidence to support a role for an inflammatory response in fibromyalgia.

Psychological and Social Effects

Although not primary causes, psychological and social factors may contribute to fibromyalgia in three ways:

• They could make individuals susceptible to fibromyalgia.
• They may play some role in triggering the onset of the condition.
• They may perpetuate, or be responsible for, the condition.

Studies have reported a greater number of severe experiences of emotional and physical abuse in patients with fibromyalgia, compared with the general population. Most often, the abuse came from family members or partners. This suggests that post-traumatic stress disorder (PTSD) or chronic stress may play a strong role in the development of fibromyalgia in some patients. PTSD is an anxiety disorder that is a reaction to a specific traumatic event. Symptoms of this condition, which can last for years after the traumatic event, include emotional withdrawal, hopelessness, irritability, mood swings, sleep problems, inability to concentrate, and an excessive startle response to noise. There is some evidence that PTSD actually results in changes in the brain, possibly from long-term over-exposure to stress hormones.