High MS Rates in Veterans: Don’t Blame the First Gulf War Zone

Military personnel serving during the first Gulf War have one of the highest incidence rates for multiple sclerosis (MS) ever reported, leading to speculation that environmental exposures in the war zone triggered the disease. Research trying to determine causes, however, came up with a surprising result: The servicemembers at the greatest risk were those who were never deployed.

By Annette M. Boyle

WASHINGTON — The first Gulf War cohort has one of the highest incidence rates for multiple sclerosis (MS) ever reported. Were the veterans at greatest risk those who:

In a surprising twist to this mystery, recent research indicates that the servicemembers most likely to develop multiple sclerosis had none of the exposures hypothesized as risk factors. Instead, the highest risk occurred in those who were not deployed in the 1990-1991 Gulf War.

“We found that there was no increase in risk across the board for any group in Gulf War I,” said Mitchell Wallin, MD, MPH, clinical associate director for the VA’s MS Center of Excellence-East and associate professor of neurology at Georgetown University School of Medicine in Washington. “That doesn’t mean deployment anywhere won’t increase risk, but deployment in the first Gulf War was not a risk factor. We didn’t look at the Operation Enduring Freedom, Operation Iraqi Freedom or Bosnia cohorts.”

Previous research by Wallin and his VA colleagues found an MS incidence rate of 7.3 per 100,000 men and 24.7 per 100,000 women in the Gulf War cohort. “The age-specific rates for the cohort are among the highest seen in comparable populations,” Wallin told U.S. Medicine, but he added that very few incidence studies exist for MS, and none includes as diverse a population base as the military study. ¹

Based on the incidence rates, looking for risk factors in deployment seemed like a logical next step for research. “The rates for MS are very high in the military, and we wanted to know what was going on. It was evident that those deployed in theater had exposures including viral infections, vaccines, air pollutants and central nervous system toxins. Could those exposures have triggered MS?”

The researchers looked at all active-duty military and activated Reserve and National Guard who served between Aug. 1, 1990, and Dec. 31, 1991. “This wasn’t a sample. There were over 1,800 cases of MS in the cohort, out of 700,000 deployed servicemembers and 1.8 million nondeployed. If there was a signal there, anything that increased risk, we would have found it,” Wallin said.

The researchers drew on medical records from the DoD and VA to find service-related cases of MS between 1990 and 2007. Among the 696,118 deployed personnel, 387 developed MS. Of the 1,786,215 nondeployed servicemembers, 1,457 incident cases of MS were found.

Deployment was not significant across almost all groups and appeared to be protective among whites, males, members of the Air Force, Army and Navy and for all groups under 44 years of age. Overall, deployed personnel had about two-thirds the risk of developing MS compared to nondeployed individuals. For whites, the relative risk was 0.62 and for blacks, 0.83.

Notably, “Marines had half the rates of other services, yet they had the longest deployments and were most likely to be deployed,” Wallin added.

A subset analysis looked at the soldiers exposed to nerve agents, including sarin and cyclosarin released when U.S. forces detonated the Khamisiyah Iraqi weapons cache in March 1991. Of the estimated 100,487 Army veterans exposed to the chemical weapons, 65 developed MS. For this group, the relative risk was a non-significant 1.10.

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