FRIDAY, July 25 (HealthDay News) -- Researchers are looking into possible geographical reasons why 1991 Gulf War veterans have developed the fatal neurological disease amyotrophic lateral sclerosis (ALS) at twice the rate of the general population.

Of the 135 diagnosed Gulf Vet cases of ALS, also known as Lou Gehrig's Disease, in the first 11 years after the war, only three had a family history of the disease. Researchers speculate this may indicate an environmental cause.

ALS causes cellular degeneration in the central nervous system. Its cause is unknown.

"There are no reports on the occurrence of ALS among veterans of other conflicts," researchers from Duke University, the University of Cincinnati and the Durham Veterans Administration Medical Center wrote in the online journal NeuroToxicology. "There is only a single report that suggests ALS may arise from environmental exposures associated with military service, per se."

A new report, published in the July issue of Neuroepidemiology, found that the cause of the ALS may have something to do with a soldiers' deployment in the Gulf between August 1990 and July 1991.

"We've found there were some areas of service where there appears to be an elevated risk," co- author Marie Lynn Miranda, an associate professor at Duke's Nicholas School of the Environment, said in a university news release.

Using multiple analyses to tie troop locations at certain times and records of possible exposures to toxic agents, the researchers identified units known to have been exposed to emissions from a munitions storage area at Khamisayah, Iraq. U.S. forces destroyed those munitions in March 1991, and a United Nations commission later found many of rockets had been loaded for chemical warfare.

A previous Defense Department modeling study stated that "some 90,000 veterans may have been exposed to low levels of nerve agent" at Khamisayah, according to new study.

Applying their research statistics, the likelihood of an environment connection with ALS in these troops "climbed as high as 91 percent," most notably in a region southeast of Khamisayah.

Miranda cautioned that more analyses is needed to add "time" to "place." For instance, the researchers need to know whether troops who developed ALS were in the path of emissions from Khamisayah on a certain day.

The team is also interested in examining environmental exposures that may be associated with smoke plumes from oil well fires.

More information

The ALS Association has more about amyotrophic lateral sclerosis.