According to preliminary results from a study probing the possible effects of chemical exposure during the Persian Gulf War, soldiers displaying multiple health-related symptoms upon their return from combat have decreased volume in two brain regions intimately linked to learning and memory.
This morning at the American Academy of Neurology's 59th Annual Meeting in Boston the study's senior investigator, Roberta White, chair of the department of environmental health at the Boston University School of Public Health, revealed early findings based on brain scans and memory tasks administered to 36 veterans.
"This study came out of a bunch of prior studies," says White, who has published multiple evaluations of both the health and cognitive state of Gulf War vets since the early 1990s.
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In one study, she noted significant cognitive deficiencies in soldiers exposed to the plume resulting from the destruction of a suspected chemical weapons depot at Khamisiyah in southeastern Iraq in March 1991. Overall, 100,000 soldiers were informed that they might have encountered the nerve agent sarin in the blast. Exposure to the poison can result in loss of control of bodily functions as well as death.
In the current study, White separated Gulf War veterans into two groups—low symptom and high symptom—based on the results of a health evaluation given to them upon return from Iraq at Ft. Devens, in Massachusetts. The average soldier reported five symptoms out of a possible 20, which included forgetfulness, headaches, fatigue, nausea, skin rash and joint pain. Half of the soldiers in the report White presented today returned from the war with more than five of these symptoms; the other half had less than five.
Using magnetic resonance imaging (MRI), White's team determined that soldiers in the high-symptom group consistently evidenced a pair of discrepancies in brain volume: Two regions, their cortex and rostral anterior cingulate gyrus were, on average, 5 percent and 6 percent smaller, respectively. (Both the cortex, the outermost layer of the brain, and the cingulate gyrus, located in the midbrain, are believed to associated with learning and memory.)
In addition, the researchers also administered a memory evaluation called the California Verbal Learning Test—wherein subjects must memorize a list of 16 words and then recall them after time has passed or other lists have been committed to memory. This test registered the vets' ability to acquire and retain information.
In behavioral findings that matched the physical deficits that White had observed in the soldier¿s brains, the high-symptom group showed some cognitive deficiency, performing, on average, 12 to 15 percent worse on the test than their low-symptom counterparts.
White says that the results revealed a statistically significant correlation between lower brain volume and poor performance on the learning test, adding that these preliminary findings suggest the physical brain discrepancies are likely "a marker for some kind of underlying central nervous system difference between high- and low-symptom groups."
Going forward, she plans to factor in the kind and amount of potentially harmful substances the soldiers were exposed to—chemicals ranging from pesticides to nerve agents, like sarin. Adding exposure into the equation, she says, "gets us much … closer to some kind of change or an effect of some kind of exposure in the Gulf."
As to whether these symptoms are part of a pathology known as "Gulf War syndrome," an illness that has been linked to immune system disruptions in troops who had served in the Gulf War, White says she cannot be sure. "I have never been able, in 16 years of research, to identify a common core group of symptoms that could be characterized as Gulf War syndrome."