Why is Amyotrophic Lateral Sclerosis (ALS) a service-connected disease?

By Dr. Colin Quinn

Veteran with ALS often ask why ALS is a service connected condition. Many believe it is due to exposures during combat such as Agent Orange. The truth is that physicians and scientists are still not aware of a direct connection between a particular exposure and the eventual development of ALS.

In 2006 the Institute of Medicine issued a report indicating “Limited and suggestive evidence of association between military service and later development of ALS” based upon several studies which demonstrated increased incidence of the disease in veterans compared to the civilian population. In 2009 the Department of Veterans Affairs issued a final ruling making ALS a presumptive service connected disease. Service connection has important implications for veterans with ALS and their families ranging from direct monthly monetary compensation to full coverage and priority for many VA services.

The studies which prompted the IOM report and the Department of Veterans Affairs ruling did not include information about specific exposures. While the initial studies which suggested an increased risk of the development of ALS in Veterans focused on the Gulf War population,1,2,3 the largest prospective study included an older population which was unlikely to have served in the Gulf4. Interestingly this study did not even distinguish between deployed and non-deployed veterans and still found an increased risk of developing ALS.

There have been attempts to survey various exposures both veterans who developed ALS and those who did not. One study suggested that some exposures (e.g. Agent Orange, ground level fumigation and others) may increase risk. The problem with this type of study is people who develop a particular disease tend to remember exposures better than those who do not.  This phenomenon, called “recall bias”, can create a false impression that particular exposures cause ALS when really they are just recalled at a higher rate in veterans who develop ALS.

It is important to remember that while the relative risk of developing ALS is increased in the veteran population, the actual risk is still quite small. ALS is an uncommon disease with an incidence between 2-4/100,000. A doubling of this risk would still mean that only 4-8/100,000 veterans would develop ALS.

Smith TC, Gray GC, Knoke JD. Is systemic lupus erythematosus, amyotrophic lateral sclerosis, or fibromyalgia associated with Persian Gulf War service? An examination of Department of Defense hospitalization data. Am J Epidemiol. 2000 Jun 1;151(11):1053-9.

Haley RW. Excess incidence of ALS in young Gulf War veterans. Neurology. 2003 Sep 23;61(6):750-6.

Horner RD et al. Occurrence of amyotrophic lateral sclerosis among Gulf War veterans. Neurology. 2003 Sep 23;61(6):742-9.

Weisskopf MG et al. Prospective study of military service and mortality from ALS. Neurology. 2005 Jan 11;64(1):32-7.

Beard JD et al. Military service, deployments, and exposures in relation to amyotrophic lateral sclerosis etiology. Environ Int. 2016 May;91:104-15.


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