There were days when even Chris Yarger questioned the existence of his Gulf War-related illness, reports CBS News Correspondent Elizabeth Kaledin.
"Am I not being tough enough or determined enough or motivated enough?" he asked himself.
But for the first time, doctors have proof that the 42-year-old veteran's extreme fatigue, weight loss, tremors and pain can be linked to his brain.
"In simple terms, what we found was evidence of brain damage," said Dr. James Fleckenstein of the University of Texas Southwestern Medical Center in Dallas.
Using highly sensitive imaging technology known as spectroscopy, doctors in Texas compared the brains of 28 veterans with symptoms like Chris Yarger's to those of 18 healthy veterans.
They zeroed in on chemicals present in the deep structures of the brain which control memory, concentration and pain.
What they found in each case was that a key chemical was in short supply.
"We believe this is due to actual structural injury to these brain cells deep in the brain, and that causes this chemical to be low in the sick veterans but normal in the well vets," said Dr. Robert Haley of the same medical center.
As many as 300,000 Gulf War veterans have complained of debilitating symptoms believed to be associated with exposure to chemicals. There's even evidence that a pill known as PB, given to service people to protect them from nerve gas, may have been the culprit.
Whatever the cause, evidence that brain damage exists in Gulf War vets is a welcome step forward.
"We can put behind us the time of controversial debate about a syndrome, about whether there is a syndrome or not, and move on to, 'there's a disease and what are we going to do about it?" said Fleckenstein.
Haley is already testing drugs that could help. "We may very well be able to find a medicine that will regenerate those nerves and maybe relieve veterans of their symptoms," he said.
It's all a relief to Chris Yarger, who is happy to know at least that the problem really is in his head.
For more information on this topic, read U-Turn On Gulf War Illness.
©1999, CBS Worldwide Inc., All Rights Reserved