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FRIDAY, June 14 (HealthDay News) -- U.S. veterans with Gulf War illness complain of different types of symptoms, and researchers now think they know why: There may be two distinct forms of the illness, depending on which areas of the brain have atrophied.
"Our findings help explain and validate what these veterans have long said about their illness," said study lead author Rakib Rayhan, a Georgetown University Medical Center researcher.
For the study, published online June 14 in the journal PLoS One, the research team conducted brain scans of 28 veterans with Gulf War illness before and after they underwent exercise stress tests. For 18 veterans, pain levels increased after exercise stress, and the scans showed a loss of brain matter in regions associated with pain regulation.
Before exercise, these 18 veterans showed increased use of a part of the brain called the basal ganglia when asked to do mental skills tasks. This increased use of the basal ganglia is also seen in people with degenerative brain disorders such as Alzheimer's disease. After exercise, these veterans lost the ability to increase the use of their basal ganglia.
The exercise stress test produced different results in the other 10 veterans. They had substantial increases in heart rate as well as deterioration in the brain stem, which regulates heart rate.
And in this group, brain scans performed during thinking tasks before exercise showed increased use of the brain's cerebellum, which is also seen in people with degenerative brain disorders. After exercise, they lost the ability to increase the use of their cerebellum.
"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 said in a Georgetown news release.
This does not mean, however, that veterans with Gulf War illness will progress to Alzheimer's or other brain diseases, he added.
Gulf War illness is believed to have affected more than 200,000 U.S. troops who served in Operation Desert Shield and Operation Desert Storm in 1990 and '91. Common symptoms, which can range from mild to debilitating, include pain; fatigue; mood and memory disruptions; and gastrointestinal, respiratory and skin problems. The causes of the illness are unclear.
-- Robert Preidt
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SOURCE: Georgetown University Medical Center, news release, June 14, 2013