TUESDAY, Sept. 13 (HealthDay News) -- Two decades after the Persian Gulf War, some veterans continue to have blood flow abnormalities in their brains that in some cases have even gotten worse, a new study finds.

These problems are part of a debilitating disorder known as Gulf War illness. Though somewhat mysterious even today, Gulf War illness is believed to be caused by exposure to neurotoxins and nerve gas. The U.S. Department of Veterans Affairs' scientific advisory committee estimates some 125,000 vets are afflicted by it.

Symptoms can include memory and concentration difficulties, fatigue, neuropathic pain, balance problems and depression.

Researchers had initially identified the abnormalities in blood flow in the brain's hippocampus -- the region associated with spatial navigation and the formation of long-term memories -- in 35 Gulf War vets in 1998. At the time, the scientists looked at blood flow using a specialized type of brain scan called single photon emission computed tomography (SPECT).

Similar abnormalities in hippocampal blood flow cropped up again 11 years later, according to the study.

The study is published online in the journal Radiology.

"We confirmed that abnormal blood flow continued or worsened over the 11-year span since first being diagnosed, which indicates that the damage is ongoing and lasts long term," said the study's principal investigator Dr. Robert W. Haley, chief of epidemiology in the departments of internal medicine and clinical sciences at the University of Texas Southwestern Medical Center in Dallas, in a Radiology Society of North American news release.

Researchers noted that their current investigation used an innovative technique known as arterial spin labeled MRI, or ASL, which "picks up brain abnormalities too subtle for regular MRI to detect."

The novel technique, they said, better diagnoses and distinguishes between the three main types of Gulf War illness, each of which are characterized by somewhat different symptoms.

More information

The U.S. Department of Veterans' Affairs provides more information on Gulf War illnesses.