Parasympathetic Nervous System at Risk Gulf War syndrome

[Hawk]

Parasympathetic Nervous System at Risk
GULF WAR SYNDROME

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.

"The high rate of gallbladder dis ease 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 Robert Haley, 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 Gulf War syndrome is so elusive and mysterious."

Exposure of U.S. troops to nerve gas in the 1991 Gulf War was more frequent and widespread than previously thought, perhaps accounting for many veterans' afflictions of gallbladder disease, depression, joint pain, and sexual dysfunction.

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 Gulf War 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," Haley explains. "Its failure to increase at night in ill Gulf War veterans may explain their unrefreshing sleep."

In previous studies, Haley 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 Gulf War. A recent report from the Government Accountability Office confirmed that exposure to low-level sarin in the 1991 Gulf War was more frequent and widespread than previously acknowledged.

Subsequent research from Haley's group showed that veterans suffering from Gulf War 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.

Copyright Society for Advancement of Education Feb 2005