Military Service Linked to Worse ALS Survival, Study Finds

Military service is linked to higher risk of a myotrophic lateral sclerosis (ALS), and a recent study found that veterans have worse survival times than nonveterans for reasons that are unclear.In an adjusted analysis of outcomes in 6908 nonveterans and 1735 veterans with ALS, military service was associated with a 25% higher mortality risk (hazard ratio, 1.25; P <.0001). The data was reported Paul Mehta, MD, principal Investigator of the National ALS Registry for the Centers for Disease Control and Prevention (CDC), et al in Muscle & Nerve. The study found that the median observed time from ALS diagnosis to death or censoring was 3.77 years for veterans and 4.79 years for nonveterans, and the estimated 5-year survival was 47.1% and 57.4%, respectively.The reasoning behind such a gap is difficult to identify, according to Daniel M. Pastula, MD, MHS, professor of neurology, infectious disease, and epidemiology at the University of Colorado Anschutz/Colorado School of Public Health.“It’s really hard to tease out the exact reason,” Pastula told Federal Practitioner in an interview. “This reflects something we all kind of know: There is something different about veterans. They are a special population.” Pastula was not involved in the study but has conducted his own research into ALS and veterans.Researchers have spent decades trying to untangle a possible connection between military service and ALS. A 2017 meta-analysis suggested 29% higher odds of ALS in military personnel vs nonmilitary personnel (pooled odds ratio, 1.29; P = .01). And a 2016 study of veterans linked a higher risk of ALS to exposure to pesticides, herbicides used for military purposes, explosions, burning agents in the field, and Agent Orange, as well as other factors. The new study tracked participants in the US National ALS Registry from 2011-2023. The 6908 nonveterans had an average age at diagnosis of 59.5 years; 50% were male; 91.5% were White, 3.2% Latino/Hispanic, 2.0% non-Hispanic Black, and 1.7% non-Hispanic Asian, and 1.6% other race. The 1735 veterans had a mean age at diagnosis of 64.4 years and 93.9% were male. Their racial/ethnic makeup was similar to the nonveteran group. The veterans were more likely than nonveterans to have ever smoked (58.7% vs. 42.8%, respectively) and to have ever used alcohol (85.7% vs. 77.5%, respectively). Limb onset was more common and bulbar onset less common in veterans than nonveterans, and researchers found no difference in survival by military branch.Military Service Isn’t Definitively Linked to Extra RiskThe CDC declined to make the study authors available for an interview.However, in response to a question about the ALS survival gap in veterans, CDC spokesperson and Senior Public Affairs Specialist Belsie González, MPH, said the cause is unclear.“Military service may be a marker for military-related exposures or other factors affecting prognosis, but our study does not establish that military service itself causes shorter survival,” González said in an interview. “Further research incorporating military exposures, comorbidities, and health care utilization is needed to better understand the association.”The study suggests delayed ALS diagnosis may play a role. The researchers highlight their own 2026 study that reported veterans were diagnosed with ALS later than nonveterans (mean 20.8 months vs 16.7 months after first symptoms, P = .0004).However, it’s not known how many of the veterans in the new study received care at the US Department of Veterans Affairs or elsewhere. Limitations and Next StepsThe study notes limitations such as reliance on self-report about military service and diagnosis date. It also does not include patients who died before they could enroll in the National ALS Registry. Moving forward, González said the CDC intends to continue its ALS in several areas.“For example, we are examining whether the military service-survival association differs across clinically relevant groups and are also analyzing ALS incidence and prevalence among veterans,” she said. “Together, this work is intended to better understand both the occurrence of ALS among veterans and what happens after diagnosis.”The CDC/Agency for Toxic Substances and Disease Registry National ALS Registry funded the study. One author discloses relationships in CDC/ATSDR National ALS Registry, the ALS Network, and the Paralyzed Veterans of America Foundation. Other authors and Pastula have no disclosures.