By: UT Southwestern Medical Center on May 02 2007 11:24:04
UT
Southwestern Medical Center at Dallas researchers have uncovered damage
in a specific, primitive portion of the nervous systems of veterans
suffering from Gulf War syndrome. UT Southwestern researchers
report that 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.
Their findings will be published in the October issue of the American
Journal of Medicine and are currently available online. "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," said Dr. Robert Haley, chief
of epidemiology at UT Southwestern and lead author of the new study. 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," said Dr. Haley. Previously, isolating pure
parasympathetic brain function was difficult. In the new study Dr.
Haley and his colleagues used a technique that monitors changes in
approximately 100,000 heartbeats over 24 hours and measures changes in
high-frequency heart rate variability -- a function solely regulated by
the parasympathetic nervous system. After plotting the subtle
changes 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," Dr. Haley said. "Its failure to increase at night in ill Gulf War
veterans may explain their unrefreshing sleep." The tests were
conducted on 40 members of a Naval Reserve construction battalion, also
known as Seabees. Both ill and healthy veterans from the same battalion
were tested for comparison. In addition, pure sympathetic
nervous system functions were tested. In these tests, there were no
appreciable differences between the two groups of veterans. Dr.
Haley first described Gulf War syndrome in a series of papers published
in January 1997 in the Journal of the American Medical Association
(JAMA). In previous studies, Dr. Haley and his colleagues 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 Dr. 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. Dr. Haley and his colleagues have
closely followed the same group of tests subjects since 1995. A new
grant from the U.S. Department of Defense will allow Dr. Haley's team
to undertake a study in a much larger sample of Gulf War veterans. Gulf War
syndrome