Posts tagged gulf war illness
Articles and news from the latest research reports.
Stress Test and Brain Scans Pinpoint Two Distinct Forms of Gulf War Illness
Researchers at Georgetown University Medical Center say their new work suggests that Gulf War illness may have two distinct forms depending on which brain regions have atrophied. Their study of Gulf War veterans, published online today in PLOS ONE, may help explain why clinicians have consistently encountered veterans with different symptoms and complaints.
Using brain imaging that was acquired before and after exercise tests, the researchers studied the effects of physical stress on the veterans and controls. Following exercise, subgroups were evident. In 18 veterans, they found that pain levels increased after completion of the exercise stress tests exercised; fMRI scans in these participants showed loss of brain matter in adjacent regions associated with pain regulation.
During cognitive tasks, this group showed an increased use of the basal ganglia — a potential compensatory strategy the brain uses that is also seen in neurodegenerative disorders such as Alzheimer’s disease. Following exercise, this group lost the ability to employ their basal ganglia, suggesting an adverse response to a physiological stressor.
In addition, “a separate group of 10 veterans had a very different clinical alteration,” says lead author Rakib Rayhan, a researcher in the lab of the study’s senior investigator, James Baraniuk, MD, a professor of medicine at GUMC.
In these 10 veterans, the researchers found substantial increases in heart rate. They also discovered that this subgroup had atrophy in the brain stem, which regulates heart rate. .
In addition, brain scans during a cognitive task performed prior to exercise showed increased compensatory use of the cerebellum, again a trait seen in neurodegenerative disorders. Like the other group, this cohort lost the ability to use this compensatory area after exercise.
Alterations in cognition, brain structure and exercise-induced symptoms found in the veterans were absent in the 10-participant matched control group, the researchers say.
“The use of other brain areas to compensate for a damaged area is seen in other disorders, such as Alzheimer’s disease, which is why we believe our data show that these veterans are suffering from central nervous system dysfunction,” Rayhan explains. He adds, however, that because such changes are similar to other neurodegenerative states, it doesn’t mean that veterans will progress to Alzheimer’s or other diseases.
These findings — a surprise to researchers — follow a study in Gulf War veterans published in March in PLOS ONE that reported abnormalities in the bundle of nerve fibers connecting the brain areas involved in the processing and perception of pain and fatigue.
Gulf War Illness is the mysterious malady believed to have affected more than 200,000 military personnel who served in the 1990-1991 Operation Desert Shield and Desert Storm.
Although veterans were exposed to nerve agents, pesticides and herbicides (among other toxic chemicals), no one has definitively linked any single exposure or underlying mechanism to Gulf War illness.
The symptoms of Gulf War illness — which have not been widely accepted by the public or medical professionals — range from mild to debilitating and can include widespread pain, fatigue and headache, as well as cognitive and gastrointestinal dysfunctions.
“Our findings help explain and validate what these veterans have long said about their illness,” Rayhan says.
Researchers Link Gulf War Illness to Physical Changes in Brain Fibers that Process Pain
Researchers at Georgetown University Medical Center (GUMC) have found what they say is evidence that veterans who suffer from “Gulf War Illness” have physical changes in their brains not seen in unaffected individuals. Brain scans of 31 veterans with the illness, compared to 20 control subjects, revealed anomalies in the bundles of nerve fibers that connect brain areas involved in the processing and perception of pain and fatigue.
The discovery, published online March 20 in PLOS ONE, could provide insight into the mysterious medical symptoms reported by more than one-fourth of the 697,000 veterans deployed to the 1990-1991 Persian Gulf War, the researchers say. These symptoms, termed Gulf War Illness, range from mild to debilitating and can include widespread pain, fatigue, and headache, as well as cognitive and gastrointestinal dysfunctions.
Although these veterans were exposed to nerve agents, pesticides and herbicides, among other toxic chemicals, no one has definitively linked any single exposure or underlying mechanism to Gulf War Illness according to the scientists.
This is the first study to show veterans, compared to unaffected subjects, have significant axonal damage. Bundles of axons, which form the brain white matter, are akin to telephone wires that carry nerve impulses between different parts of the gray matter in the brain. The researchers found that damage to the right inferior fronto-occipital fasciculus was significantly correlated with the severity of pain, fatigue, and tenderness.
“This tract of axons links cortical gray matter regions involved in fatigue, pain, emotional and reward processing. This bundle also supports activity in the ventral attention network, which searches for unexpected signals in the surrounding environment that may be inappropriately interpreted as causing pain or being dangerous. Altered function in this tract may explain the increased vigilance and distractibility observed in veterans.” says lead author Rakib Rayhan, MS, a researcher in the lab of the study’s senior investigator, James Baraniuk, MD, a professor of medicine at GUMC.
In this Department of Defense-funded study, the research team used a form of functional magnetic resonance imaging (fMRI) called diffusion tensor imaging. This imaging method examines patterns of water diffusion in the brain to look for changes in the integrity of white matter, which is not seen on regular MRI scans. “This provides a completely new perspective on Gulf War Illness,” says Baraniuk. “While we can’t exactly tell how this tract is affected at the molecular level — the scans tell us these axons are not working in a normal fashion.”
Although preliminary, “the changes appear distinct from multiple sclerosis, major depression, Alzheimer’s disease and other neurodegenerative diseases,” says Rayhan. “These novel findings are really exciting because they provide validation for many veterans who have long said that no one believes them.”
The results must be replicated, say its authors, but for the first time a potential biomarker for Gulf War Illness may be on the horizon as well as a possible target for therapy aimed at regenerating these neurons.
“Pain and fatigue are perceptions, just like other sensory input, and Gulf War Illness could be due to extensive damage to the structures that facilitate them,” says Rayhan. “Some of the veterans we studied feel pain when doing something as simple as putting on a shirt. Now we have something to tell them about why their lives have been so greatly affected.”
(Source: explore.georgetown.edu)