Low IGF-1 Levels. Some studies have reported low levels of insulin-like growth factor-1 (IGF-1) in about a third of fibromyalgia patients. IGF-1 is a hormone that promotes bone and muscle growth. Low levels of growth hormone may lead to impaired thinking, lack of energy, muscle weakness, and intolerance to cold. Studies suggest that changes in growth hormone likely stem from the hypothalamus in the brain. Although researchers have not found a link between IGF-1 levels and fibromyalgia, growth hormone levels in the blood may be a marker of the disorder.
Abnormal Pain Perception and Substance P. Some studies have suggested that people with fibromyalgia may perceive pain differently than healthy people. 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 found abnormalities in pain processing centers. For example, researchers have detected up to three times the normal level of substance P (a chemical messenger associated with increased pain perception) in the cerebrospinal fluid of fibromyalgia patients.
Some fibromyalgia patients may be oversensitive to external stimulation, and overly anxious about the sensation of pain. This increase in awareness is called generalized hypervigilance.
A conflict between sensory perception and nervous system processing might occur in people with fibromyalgia. Fibromyalgia patients have been found to have greater awareness of, or less tolerance for, movement problems (such as tremor) that don't match their expected sensory feedback. This mismatch in sensory signals might enhance the perception of pain. Fibromyalgia patients also seem to be more sensitive to sounds.
Immune Abnormalities
Fibromyalgia has 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.
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Review Date: 12/27/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine,
Harvard Medical School; Physician, Massachusetts General Hospital.
Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M.,
Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
