Parasympathetic nervous system at risk

Damage to the parasympathetic nervous system may account for nearly half of the typical symptoms-including gallbladder disease, unrefreshing sleep, depression, joint pain, chronic diarrhea, and sexual dysfunction-that afflict those with Gulf War syndrome, according to a study by the University of Texas Southwestern Medical Center at Dallas.

Parasympathetic nervous system

"The high rate of gallbladder disease in these men, reported in a previous study, is particularly disturbing because typically women over 40 get this. It's singularly rare in young men," states lead author and chief of epidemiology.

The parasympathetic system regulates primitive, automatic bodily functions such as digestion and sleep, while the sympathetic nervous system controls the "fight or flight" instinct. "They're sort of the mirror image of each other--the yin and the yang of the nervous system-that control functions we are not usually aware of. This is another part of the explanation as to why syndrome is so elusive and mysterious:'

Previously, isolating pure parasympathetic brain function was difficult. Haley and his colleagues, however, used a technique that monitors fluctuations in approximately 100,000 heartbeats over 24 hours and measures fluctuations in high-frequency heart-rate variability--a function solely regulated by the parasympathetic nervous system.

After plotting the subtle alterations in heart function using a mathematical technique called spectral analysis, researchers found that parasympathetic brain function, which usually peaks during sleep, barely changed in veterans with syndrome even though they appeared to be sleeping. In a group of well veterans tested for comparison, the brain functions increased normally.

"The parasympathetic nervous system takes care of restorative functions of the body. During sleep it's orchestrating that process, which is why we feel refreshed when we wake up;' explains. "Its failure to increase at night in ill veterans may explain their unrefreshing sleep."

In previous studies, presented evidence attributing the veterans' illness to low-level exposure to sarin gas--a potent nerve toxin which drifted over thousands of soldiers when U.S. forces detonated Iraqi chemical stores during and after the. A recent report from the Government Accountability Office confirmed that exposure to low-level satin in the 1991 Gulf War was more frequent and widespread than previously acknowledged.

Subsequent research from group showed that veterans suffering from syndrome also were born with lower levels of a protective blood enzyme called paraoxonase, which usually fights off the toxins found in sarin. Veterans who were in the same area and did not get sick had higher levels of this enzyme.