SINGAPORE: Chronic fatigue syndrome (CFS) is not a psychological condition as previously thought, said researchers who have found evidence that it is caused by changes in brain chemistry.
CFS, also known as myalgic encephalomyelitis or ME, is characterised by physical and mental fatigue, pain and cognitive dysfunction.
The study conducted by Georgetown University Medical Center discovered that CFS is caused by a brain molecule called miRNA. Its changing levels can bring about tiring symptoms.
For comparison, the researchers also studied patients with Gulf War Illness (GWI), which causes similar symptoms, including chronic fatigue, fibromyalgia and joint pain.
The name "Gulf War Illness" was given to the condition that veterans deployed to the 1990 to 1991 Persian Gulf War experienced after being exposed to nerve agents, pesticides and other toxic chemicals. More than one quarter of the 697,000 veterans had GWI.
The Georgetown University Medical Center researchers, who performed spinal taps on participants with CFS, veterans with GWI, and a control group to assess their miRNA levels, found that they all had the same levels.
However, after riding stationary bikes for 25 minutes, CFS patients had reduced levels of 12 different miRNAs than non-CFS patients. Unlike the CFS participants, the GWI group developed jumps in heart rate when standing up that lasted for two to three days after exercise.
Scans on GWI patients revealed they had smaller brain stems in regions that control heart rate, and did not activate their brains when doing a cognitive task.
Senior investigator Dr James Baraniuk said that the miRNA levels in CFS were different from the ones that are altered in depression, fibromyalgia, and Alzheimer's disease, further suggesting CFS and Gulf War Illness are distinct diseases.
Although the exact causes of CFS are still unknown, the findings would be welcomed by patients who have been misdiagnosed and instead, treated for depression or other mental disorders, said Prof Baraniuk.
CFS should not be mistaken for tiredness. The US Centers for Disease Control and Prevention's criteria for the condition included a moderate or severe, persistent fatigue that lasts for more than six months and impairs daily activities.
Other criteria consisted of short-term memory or problems with concentration, sore throat, sore lymph nodes, sleep disturbances, and the new onset of headaches, including migraine.