Possible New Cause of Chronic Fatigue Syndrome Identified
WebMD News Archive
May 29, 2001 -- Yet another potential cause of chronic fatigue syndrome has been uncovered, this time by an Australian group of researchers. They implicate an abnormality in a body system called the anandamide system, but a U.S. chronic fatigue syndrome expert is not convinced by their early findings.
Chronic fatigue syndrome, or CFS for short, is a poorly understood condition or collection of conditions that cause a variety of symptoms such as substantial fatigue, muscle pain, sore throat, emotional instability, and difficulty concentrating. These symptoms persist for six months or more and are not explained by any other known medical condition.
Experts are in disagreement as to the cause or causes of CFS, but a popular theory today is that it is an autoimmune disorder. This means that the immune system has somehow been directed to attack the body itself. Many CFS experts have changed the name of this disorder to chronic fatigue and immune dysfunction syndrome (CFIDS) to reflect the role of the immune system.
Another popular theory is that CFS is caused by infection with a bacteria or virus, which may persist in people with CFS or which may have occurred in the past and triggered the immune system to function abnormally. According to the CFIDS Association of America, approximately 422 of every 100,000 Americans suffer from CFS.
Researchers from Australia have linked CFS to the anandamide system in the body, which is responsible for regulating several aspects of bodily function, including the brain, heart, gut, and immune system. They found that a toxin released from bacteria that is present in high levels in people with CFS causes the anandamide system to work abnormally by releasing too many anandamides.
Co-author Timothy Kilgour Roberts, PhD, associate professor at the School of Biological and Chemical Sciences at the University of Newcastle in Australia, tells WebMD that "the many manifestations of CFS may represent a bacterial toxin interfering with the anandamide [system.]"
He and his colleagues injected rats with a toxin, called delta-hemolysin, that is produced by some types of bacteria and that they had found to be present in many CFS sufferers. Given on its own, this toxin caused the rats to have fever and pain. However, when the toxin was given along with a drug that blocks the effect of anandamides, the rats did not experience pain or fever.
Though the findings are too preliminary to indicate how they might impact people with CFS, the investigators speculate that they may lead to new therapies such as antibiotics to destroy the bacteria that produce the offending toxin. The investigators presented their findings recently at an immunology conference in Utrecht, Netherlands.
Expert Jay A. Goldstein, MD, a researcher and clinician specializing in CFS who is in private practice in Orange, Calif., does not agree that anandamides are a likely culprit in CFS. He says that the hundreds of studies that have been conducted on the anandamide system to date show that, rather than contribute to the symptoms of CFS, anandamides actually help reduce them. For instance, anandamides stimulate brain chemicals responsible for blocking anxiety and panic, common problems in people with CFS.