Background: Two recent studies suggest that the risk of ALS is increased among Gulf War veterans. It is not known whether military service outside of the Gulf War is associated with increased risk of ALS.
Methods: The authors prospectively assessed the relation between service in the military and ALS mortality among participants in the Cancer Prevention Study II cohort of the American Cancer Society, a cohort that includes over 500,000 men from the 50 states, Washington, DC, and Puerto Rico. Participant follow-up was conducted from 1989 through 1998 for ALS mortality. There were a total of 280 deaths from ALS among 126,414 men who did not serve in the military and 281,874 who did. Adjusted relative risks (RRs) were calculated using Mantel-Haenszel weights and Cox proportional hazards.
Results: Men who served in the military had an increased death rate from ALS (RR = 1.53; 95% CI: 1.12 to 2.09; p = 0.007) compared with those who did not serve. The increase in ALS mortality was observed among men who served in the Army or National Guard (RR = 1.54), Navy (RR = 1.87), Air Force (RR = 1.54), and Coast Guard (RR = 2.24); no increase in risk was found in men who served in the Marine Corps, although there were only 13,670 men in this group. The risk of ALS among men who served was elevated in every 5-year birth cohort from 1915 through 1939.
Conclusions: Military personnel have an increased risk of ALS. This increase appeared to be largely independent of the branch of service and the time period served.