Sympathetic Nervous System
No one really knows what causes the debilitating medical condition known as fibromyalgia syndrome (FMS) and so the American Fibromyalgia Syndrome Association has worked hard at funding promising avenues of research in the field. One of the newest projects AFSA has taken under its wings is the work of Manuel Martinez-Lavin, M.D. who explores the possible genetic causes of FMS.
Martinez-Lavin, of Mexico City's National Institute of Cardiology is convinced that the body's fight or flight response is the root cause of many fibromyalgia symptoms. This classic sympathetic nervous system response to stress has been well-documented, but not explored as a specific cause of fibromyalgia symptoms until now.
Matinez-Lavin also believes that FMS is linked to genetic factors that change the workings of the sympathetic nervous system. The sympathetic branch is one of two aspects of the autonomic nervous system, which includes both the sympathetic and parasympathetic systems.
The just-published study is an evaluation of the variations in genes that control the speed of the enzyme known as catechol-O-methyltrasferase (COMT). COMT is responsible for breaking down dopamine, norepinephrine, and epinephrine so that the body can eliminate them. But when there are genetic irregularities, the COMT enzyme becomes sluggish. This causes a buildup of norepinephrine and epinephrine, which are used by the sympathetic nervous system as transmission vehicles. According to this theory, the resultant hyperactivity is the cause of FMS and stems from a genetic abnormality.
Martinez-Lavin spoke of a study on 202 healthy women, commenting, “Women who slowly degraded the catecholamines are more sensitive to pain.” The physician adds that six variations of the COMT gene are known to lead to sluggish enzymes and those with these variations have been found to be more vulnerable to the condition known as temporomandibular dysfunction (TMD), which causes chronic pain in the face around the jaw area.
Specific ethnic factors do influence the observed variations in the COMT gene. Therefore, Martinez-Lavin studied two separate populations: Spanish women and Mexican women. In a study of 160 Spanish women, 80 with and 80 without FMS, a higher incidence was found in three of the known variations on the COMT gene. “In the Spanish people, there was a clear relationship between the number of defects in the COMT gene and FMS severity, according to the Fibromyalgia Impact Questionnaire (FIQ),” says Martinez-Lavin, "whereas, in the Mexican population, there was only a slight correlation with two sub-scales of the FIQ.”