Chronic fatigue syndrome and Gulf War illness are distinct syndromes

Researchers at Georgetown University have found two distinct molecular signatures in the brain disorders chronic fatigue syndrome (CFS) and Gulf War Illness (GWI). In the past many doctors have told patients suffering from these syndromes that the disorders are psychological in origin so this news may come as useful to patients. The work also showed two variants of GWI. The two brain disorders share have many of the commonalities, such as fatigue, pain, exhaustion after exercise, and cognitive dysfunction.

According to the National Academy of Medicine, chronic fatigue syndrome affects between 836,000 and 2.5 million Americans. The disorder was believed to be psychological in origin until a 2015 review of 9,000 articles pointed to unspecified biological causes.  Gulf War Illness has developed in more than one-fourth of the 697,000 veterans in the U.S. who were in the 1990-1991 Persian Gulf War. Gulf War veterans were exposed to combinations of nerve agents, pesticides, and other toxic chemicals that may have triggered their cognitive, chronic pain, and gastrointestinal problems.

The researchers found changes in brain chemistry by looking at levels of miRNAs that turn protein production on or off 24 hours after participants rode a stationary bike for 25 minutes. The researchers saw three different patterns in the brain’s production in the CFS group and the two GWI phenotypes. The researched collected on spinal fluid of CFS, GWI, and controls who were okay with having a lumbar puncture. Spinal taps before exercise showed miRNA levels were the same in all participants. In contrast, miRNA levels in spinal fluid were significantly different after exercise. The CFS group, two GWI groups, and control group had distinct patterns of change. CFS participants had reduced levels of 12 different miRNAs after exericse, compared to those who did not exercise. The miRNA changes in the two GWI subtypes had differences after exercise. One subgroup of GWI developed jumps in their heart rate of over 30 beats when standing up that lasted for several days after exercise. Magnetic resonance imaging showed these participants had smaller brainstems in regions that control heart rate, and their brains were not activated when doing a cognitive task. The other subgroup of GWI did not have any heart rate or brainstem changes, but additional brain regions were activated on a memory test. The two groups of GWI were different from each other just like they were different from the CFS group and control group.

The researchers say that the miRNA levels in CFS and GWI were different from the the miRNA levels in those with in fibromyalgia, depression and Alzheimer’s disease. This work suggests that CFS and GWI are distinct diseases and thus more research is needed to help explore better treatments. See also the post for more discussion on chronic fatigue syndrome.

Reference: James N. Baraniuk and Narayan Shivapurkar, Exercise – induced changes in cerebrospinal fluid miRNAs in Gulf War Illness, Chronic Fatigue Syndrome and sedentary control subjects, Scientific Reports, vol. 7, issue 1, 2017.

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