(DETROIT FREE PRESS) -- A small number of studies have suggested military veterans may be at a higher risk for developing ALS.
It's enough evidence that, in 2008, the Department of Veterans Affairs began setting aside benefits specifically for anyone who had been in the service and developed the disease.
Although benefits vary depending on service time and other factors, ALS was categorized as a "presumptively compensable illness." In other words, veterans diagnosed with ALS are eligible for monthly disability pay and funds to modify their homes, vehicles to transport them, insurance for dependents and survivors' benefits.
From January 2003 to September 2011, Veterans Affairs - prompted by anecdotal reports of young veterans returning from the Persian Gulf War and developing ALS - collected information and even blood samples from willing veterans with ALS, said Dr. Eugene Oddone, who ran the registry and is now director of the Center for Health Services Research in Primary Care at the VA Medical Center in Durham, N.C.
The goal was to determine whether ALS really was more prevalent among veterans and, if so, among which veterans and why. The results were mixed.
Several studies suggested an increased incidence among veterans whose service dated as far back as 1910. One study concluded that veterans were 50 percent more likely to develop ALS than the general population.
Still, "at the end of the day, we were talking about small numbers," Oddone said.
Researchers also were unable to determine a single common denominator among those with ALS.
One study concluded they had slightly elevated lead levels in their blood, though it was unclear whether that was significant, Oddone said.
Other researchers over time have suggested, but never found conclusive evidence, that ALS is linked to head trauma, pesticides or burning oil fields.
It may be a genetic predisposition to ALS that is triggered by a number of factors, said Pat Wildman, director of public policy for the ALS Association, a Washington-based advocacy group.
"It's a lot more complicated than we think, and there are probably a lot of factors at play," he said.
In 2006, the National Academy of Sciences' Institute of Medicine (IOM) reviewed the studies, concluding the data were "limited and suggestive" of a link between military service and ALS.
The Veterans Administration ALS registry closed in 2011, replaced the following month - partly at the urging of the ALS Association - with another national registry. That registry, run by the Centers for Disease Control and Prevention, is not limited to veterans and asks enrollees questions not only about any military service and work, but also about family and health history, and lifestyle.
It can be found at www.cdc.gov/als.