About one in 8 war veterans develop some sort of mental disorder related to having been in combat.

A newly identified disorder called Gulf War illness (GWI) has affected close to 30 percent of the military personnel who served in the 1990-1991 Persian Gulf War. The ailment is similar to post traumatic stress disorder, though people with GWI have symptoms unrelated to other mental ailments after times of high stress.

One might expect most Gulf War veterans to face posttraumatic stress disorder, a condition characterized by anxiety and flashbacks caused by a traumatic event like facing death, rape, or killing others. Its symptoms appear three months after exposure to a traumatic event and include flashbacks, avoidance of once enjoyed activities, depression, memory issues, and hopelessness. Gulf War veterans, however, show slightly different symptoms, feeling great deals of muscular pain unrelated to injuries or even depression. Similarly, their memories are significantly altered, leading researchers to believe that they have an entirely different ailment.

In a new study, researchers at Georgetown University have identified two distinct forms of GWI where the veterans' brains have actually atrophied, or died from over use. Symptoms of these veterans include cognitive impairment, widespread aches and pains, and tremors.

In the study, 28 Gulf War veterans were given two-day stress tests. The stress tests tested their perseverance after performing rigorous exercise; their heart rates and levels of fatigue were measured and compared to non-Gulf War veterans. After testing, 68 percent of Gulf War veterans showed signs of chronic fatigue syndrome and fibromyalgia in joints and muscles. Similarly, after only the first stress test, 10 of the veterans showed signs of tachycardia, or quickening of heart rate, which weakens and overworks the heart muscles.

Upon testing their memory retention, the researchers found that Gulf War veterans had significantly lower memory accuracy than control groups. Similarly, when asked to remember something after a stress test, fewer veterans could provide a correct answer.

When the brain structures of control people and Gulf War veterans were compared, they found that pain processing centers were more activated in the veterans, and brain regions around the pain centers had also atrophied. This could have led to increased pain perception and fatigue, as the brains of these veterans are constantly screaming that they are in pain. Brain structure and exercise-induced symptoms found in the veterans were absent in the 10-participant matched control group

This is not altogether unusual. Lead author Rakib Rayhan, Ph.D., said, "The use of other brain areas to compensate for a damaged area is seen in other disorders, such as Alzheimer's disease, which is why we believe our data show that these veterans are suffering from central nervous system dysfunction." He added that just because these changes to the brain are similar to other neurodegenerative disorders like Alzheimer's disease, it doesn't mean that veterans will progress to Alzheimer's or other diseases. Similarly, the atrophy could be caused by the overuse of certain brain regions after trauma.

The researchers feel they have identified two specific types of this Gulf War Illness — one that affects the heart and another that affects the brain. They may be intertwined, but the fact that this trauma can affect two of the body's major systems is a significant finding. While the study did not find the mechanisms by which these events occur to the war veterans, further research may enlighten how exactly this disorder is different from common postwar disorders and what exactly may be the cause.

Source: Rayhan RU, Stevens BW, Raksit MP, et al. Exercise challenge in Gulf War Illness reveals two subgroups with altered brain 1 structure and function. PLOS ONE. 2013.