This article by Rose L. Thayer originally appeared on Stripes.com. Stars and Stripes serves the U.S. military community by providing editorially independent news and information around the world.

A new medical study found that the wide-ranging symptoms of Gulf War illness appear to be caused by a failure of cells to produce adequate energy, bringing experts a step closer to finding the root cause and a treatment.

The study, released Thursday in the peer-reviewed journal “Scientific Reports,” builds on 30 years’ worth of research from project lead, Dr. Robert Haley, an epidemiologist at the University of Texas Southwestern Medical Center in Dallas.

“This is an important clue because it narrows things down,” Haley said Wednesday in a phone interview. “Now we’re trying to find the sweet spot that we could treat … and then we have a really good chance of finding a treatment.”

Following the Gulf War, which ended in 1991, returning veterans began reporting a wide range of chronic symptoms, including fatigue, fever, night sweats, memory and concentration problems, difficulty finding words, diarrhea, sexual dysfunction and body pain. The illness affects more than 25% of the 700,000 military personnel involved in the war, according to the research report.

[RELATED: CDC Formally Recognizes Gulf War Illness]

Since then, academic researchers and the Department of Veterans Affairs have been looking for the cause among the many toxic exposures that veterans faced, such as burning oil wells, pesticides, nerve gas and anti-nerve gas medication, and depleted uranium.

At one point, it was even believed that it was the stress of war that caused the symptoms, Haley said. However, his own research released in 2022 linked the onset of Gulf War illness to some veterans’ exposure to sarin, a deadly nerve gas.

Sarin, which the military has confirmed was present during the war, is a toxic, synthetic nerve agent that was first developed as a pesticide. It has been used in chemical warfare, and its production was banned in 1997.

When people are exposed to either the liquid or gas form, sarin enters the body through the skin or airways and attacks the nervous system. High levels of exposure often result in death, but studies of survivors have revealed that lower-level sarin exposure can lead to long-term impairment of brain function, according to the Texas university’s research.

[FROM VA.GOV: Gulf War Veterans’ Illnesses]

Last month, the Centers for Disease Control and Prevention recognized Gulf War illness as a legitimate medical condition linked to military service and created a medical diagnostic code for it. This move enabled doctors and scientists to more effectively track, document and treat patients. 

In this latest study, which was funded through the Department of Veterans Affairs and the Army, Haley’s team looked at 39 specialized images of the brains of Gulf War veterans with the illness and 16 without it. The brain scans came from members of the Navy Reserve’s 24th Naval Mobile Construction (Seabees) Battalion — a group that Haley has followed since 1995.

MRI experts Richard Briggs and Sergey Cheshkov worked on the study to evaluate the scans and collect data, and the team found that those veterans with Gulf War illness had dysfunctional mitochondria, the structures responsible for generating the energy cells need to function. They identified this dysfunction based on increased creatine levels, Haley said.

“These veterans don’t have damaged neurons — which would be incurable — but an energy imbalance,” he said. “That suggests their symptoms could respond to new treatments.”

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Haley studied brain scans about 25 years ago, but technology wasn’t advanced enough for him to pinpoint — as he has in this study — what exactly was going wrong in the brain cells.

With this information now confirmed, he’s focusing on moving upstream from the problem to find a root cause. That is where any future treatment would need to focus.

“That would be the Holy Grail of this 30-year-long quest. If we find that and can find a medication that can restore it to normal functioning, everything might just get better,” he said.