TUESDAY, May 1 (HealthDay News) -- Veterans of the first Gulf War who developed numerous health complaints have areas of the brain that are measurably smaller than those of healthier vets, a new study found.

The results of the U.S. government-funded study are preliminary but provide some of the first hard evidence that veterans from the 1990-1991 conflict are suffering from a real neurological illness, researchers say.

"Right now, for Gulf War veterans, there is a discounting of there being any physical basis for what might be wrong with them. But I think that what is really important about this brain imaging research is that it suggests that we really need to take their symptoms seriously, that there is a clear neurological basis for their complaints," said study lead researcher Roberta White of Boston University School of Public Health.

Another expert with a long history of research into so-called Gulf War syndrome was more cautious.

"These findings are intriguing, but they do not prove that veterans of the first Gulf War were harmed by wartime chemical exposure," said Dr. Daniel Clauw, professor of medicine and director of the Chronic Pain and Fatigue Research Center at the University of Michigan, in Ann Arbor.

The study was expected to be presented Tuesday at the annual meeting of the American Academy of Neurology, in Boston.

U.S. and British veterans of the first Gulf War have long complained of a wide array of physical and mental symptoms, which many blame on exposure to biowarfare agents such as toxic pesticides and sarin gas.

"Back when the vets first started returning from the war, they were complaining of symptoms that affected the central nervous symptom, or suggested effects on the central nervous system," White said. Those symptoms included mood swings, personality changes, disordered sleep, joint pain, headaches, skin conditions, chronic fatigue and other effects.

But, it has been tough for experts to pinpoint any "objective evidence" -- for example, anatomical anomalies -- supporting the existence of an identifiable neurological condition, White said.

But recent advances in brain imaging are helping that effort.

In its study, which is ongoing, White's team took detailed MRI images of the brains of 36 veterans of the first Iraq conflict. Half of the veterans have complained of five or more symptoms -- out of a list of 20 -- attributed to Gulf War syndrome, while the other half have listed less than five symptoms.

The brain scans revealed key differences between the two groups.

First, the cortex -- the covering of the brain, highly involved in learning -- was about 5 percent smaller in those veterans with a higher number of symptoms compared with those with a lower number of symptoms. And a second area of the brain, called the rostral anterior cingulated gyrus -- important to emotion, motivation and memory -- was 6 percent smaller on average in the more symptomatic vets, according to the study.

These finds are preliminary and do not confirm that wartime exposures changed the veterans' brains, only that differences exist, White said.

However, the brain differences may be relevant to reported symptoms "because [veterans] complain of fatigue, of changes in their cognitive efficiency, and memory problems," she noted. "We actually have objective evidence that memory performances were worse among the high-symptom complainers and that correlates with the findings in the cingulated gyrus," White added.

Those symptoms also correlate with exposures to a variety of toxins present in the first Iraq conflict, White said. "Things like pesticides, sarin -- chemical warfare agents of the kind that they used in the Gulf -- those kinds of substances do cause these kinds of effects on brain function," she said. However, she added that "much less is known about more subtle effects on brain structure of these chemicals, because they have not been studied in this way."

Another expert in Gulf War syndrome agreed that it's impossible at this point to conclude that wartime exposures led to changes in veterans' brains.

For example, "we know that many psychiatric disorders, such as depression and post-traumatic stress disorder, cause cognitive problems. And we know that these two can be associated with changes in brain function and metabolism," said Dr. Simon Wessely, a professor of psychiatry at the King's Center for Military Health Research at King's College London.

Until White's group can get a larger number of study subjects and tease out these possible confounding causes, scientists shouldn't get "too excited" about the findings, he said.

"The symptoms of Gulf War illness are very common in people who have not been to the Gulf," Wessely noted. "I would be more interested in comparing Gulf [veterans] vs. civilians with the same symptoms before I jumped to any conclusions about any relation to Gulf War exposures," he said.

Clauw seconded that thought.

"Recent, similar studies have shown decreases in brain volumes in individuals in the general population with chronic pain conditions such as low back pain and fibromyalgia," he said. "Future studies need to compare the results of brain scans of Gulf War veterans with individuals with chronic pain and other symptoms who were not deployed to the Gulf War, before concluding that any changes are due to wartime exposures."

White agreed that it's still too early to draw any definite conclusions. She said the study, which was funded by the U.S. Department of Veterans Affairs, should wrap up by this fall.

"These are preliminary findings, and, with more subjects, we might learn more about which parts of the brain are more affected," she said. Still, she added, "I think this is a very important next chapter in looking at the first Gulf War."

More information

There's more on Gulf War syndrome at the University of Chicago Medical Center.