Causes and Risk Factors of Fibromyalgia

No one knows what causes fibromyalgia, and that can be an unnerving fact to the four million people in the United States who are believed to have the disorder. Some scientists have suggested that fibromyalgia is a central sensitization disorder, in which nerve cells in the brain and spinal cord are either hyper-reactive or the inhibitory systems meant to temper the processing of pain signals are underactive.

Others believe that fibromyalgia is the result (entirely or in part) of psychological stresses. While no one can really pinpoint a definite cause at this time, there is agreement that fibromyalgia is a multi-dimensional condition with some known risk factors, including gender, age, stress level, and genetics.

Gender

Statistically speaking, women are more likely to get fibromyalgia than men. Around 75%-90% of those diagnosed with fibromyalgia are women of middle age. While the reason for this not entirely clear, sex hormones may play a role in not only the distribution of the disease but the frequency and severity of symptoms.

Other cases appear to coincide with the onset of menopause, in which hormone levels drop dramatically. This further supports a role of estrogen in flares tied to premenstrual syndrome, where cyclic decreases in estrogen could lead to increased pain.

Testosterone levels drop too, suggesting that changes in the "male hormone" (which is actually present in both sexes) may also play a role in the development of fibromyalgia symptoms. While research is lacking, a 2010 study from the University of Nebraska Medical Center showed that the progressive declines in testosterone levels as a man ages are mirrored by increases in the frequency and severity of musculoskeletal pain characteristic of fibromyalgia.

Some researchers suggest that the rate of fibromyalgia among men may, in fact, be far higher than estimated, particularly since men are less likely to seek treatment for chronic generalized pain than women.

Age

Many people consider fibromyalgia to be a disorder affecting post-menopausal women, a perception largely influenced by TV ads for fibromyalgia drugs that almost exclusively cast women in their 50s and 60s as patients. In fact, fibromyalgia most often develops during a woman's childbearing years and is most commonly diagnosed between the ages of 20 and 50.

By and large, though, the risk tends to increase as you get older. While the overall prevalence of fibromyalgia in the general population is between 2% and 4%, it will increase with age to about 8% among those around 70 years of age.

Less commonly, fibromyalgia can strike children and teens in an uncharacteristic form of the disorder known as juvenile fibromyalgia syndrome (JFMS).

Psychological Stress

Stress may also be a precipitating factor for fibromyalgia, although somewhat of a chicken-and-egg situation. While it's known, for example, that fibromyalgia frequently co-occurs with such stress-related disorders as chronic fatigue syndrome (CFS), depression, irritable bowel syndrome (IBS), and post-traumatic stress disorder (PTSD), how exactly those relationships work isn't.

With conditions like PTSD, the association seems to suggest that psychological symptoms can in some way trigger physical ones, either somatically (by altering physiologic functions), psychosomatically, or both. With CFS, depression, and IBS, the relationships may be more cause-and-effect, with certain psychologic stresses triggering physical symptoms and certain physical symptoms triggering psychological/cognitive ones.

Research into the mixed nature of fibromyalgia suggests that there may four subtypes:

• Fibromyalgia with no psychiatric conditions
• Fibromyalgia with pain-related depression
• Fibromyalgia co-occurring with clinical depression
• Fibromyalgia due to somatization (the tendency to experience psychological distress with physical symptoms, such as can occur with PTSD)

Similarly, sleep problems are characteristically associated with fibromyalgia. While certain sleep disorders like obstructive sleep apnea can co-exist with fibromyalgia and contribute to high rates of chronic fatigue, other sleep-related issues like sleep starts (hypnic jerks) and broken sleep are believed to be a consequence of neurotransmitter dysfunction in the central nervous system.

Whatever the cause or effect, restorative sleep (in which sleep patterns are normalized) are directly linked to a reduction in pain symptoms.

Genetics

Genetics appear to play a part in the development of fibromyalgia, although this may be due to multiple genetic variants, rather than a single one. At present, scientists have yet to unlock the combination from the hundreds of possible pain-regulating genes in your body.

While research is ongoing, there is some evidence that people with the so-called 5-HT2A receptor 102T/C polymorphism may be at higher risk of fibromyalgia.