Exercise alters brain activation in Gulf War Illness and Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome, by Stuart D Washington, Rakib U Rayhan, Richard Garner, Destie Provenzano, Kristina Zajur, Florencia Martinez Addiego, John W VanMeter, James N Baraniuk in Brain Communications, Vol 2, Issue 2, 2020, fcaa070 [doi.org/10.1093/braincomms/fcaa070] Published: 10 August 2020
Gulf War Illness affects 25–30% of American veterans deployed to the 1990–91 Persian Gulf War and is characterized by cognitive post-exertional malaise following physical effort. Gulf War Illness remains controversial since cognitive post-exertional malaise is also present in the more common Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
An objective dissociation between neural substrates for cognitive post-exertional malaise in Gulf War Illness and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome would represent a biological basis for diagnostically distinguishing these two illnesses.
Here, we used functional magnetic resonance imaging to measure neural activity in healthy controls and patients with Gulf War Illness and Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome during an N-back working memory task both before and after exercise. Whole brain activation during working memory (2-Back > 0-Back) was equal between groups prior to exercise.
Exercise had no effect on neural activity in healthy controls yet caused deactivation within dorsal midbrain and cerebellar vermis in Gulf War Illness relative to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients. Further, exercise caused increased activation among Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients within the dorsal midbrain, left operculo-insular cortex (Rolandic operculum) and right middle insula.
These regions-of-interest underlie threat assessment, pain, interoception, negative emotion and vigilant attention. As they only emerge post-exercise, these regional differences likely represent neural substrates of cognitive post-exertional malaise useful for developing distinct diagnostic criteria for Gulf War Illness and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
The functional magnetic resonance imaging (fMRI) results showed that the brain activity of Gulf War veterans behaved differently from CFS patients after exercise and memory tasks. GWI patients had lower brain activity in the part of the brain that processes pain (periaqueductal gray) as well as in the cerebellum. The cerebellum controls motor skills, cognition, and emotions.
The opposite was found in patients CFS, with increased activity in the two brain areas which increased attention and vigilance. Despite no changes in brain activity, CFS still suffered several physical symptoms and episodes of brain fog. Previous evidence has shown how the molecular structure of the cerebrospinal fluid in patients of both conditions alter after moderate exercise.
The two illnesses share many symptoms, including cognitive and memory problems (often described as “brain fog”), pain, and fatigue following mild to moderate exercise. Some medical institutions, including the U.S. Department of Veterans Affairs (the VA), list CFS as a symptom of GWI (called chronic multisymptom illness associated with service in the Gulf War by the VA).
“Our results strongly suggest that GWI and CFS represent two distinct disorders of the brain and therefore CFS is not a symptom of GWI,” says Stuart Washington, Ph.D., a post-doctoral fellow and first author on the study. “Combining of two different disorders could lead to improper treatment of both.” Washington works in the laboratory of James Baraniuk, MD, professor of medicine at Georgetown.