New research indicates that the risk of developing amyotrophic lateral sclerosis, or ALS, among United States veterans varies by military branch and rank, with higher rates observed in the Air Force, Navy and Coast Guard, and among officers compared with Army veterans and enlisted personnel. The study, published in Neurology, used a vast medical records dataset to explore these differences.
Researchers analysed electronic health records from the Veterans Health Administration, focusing on care received between January 2000 and October 2024. To identify new ALS cases, they included only veterans with at least two years of medical history in the system before diagnosis. The sample comprised more than 9.1 million men and almost 785,000 women, among whom 13,935 men and 484 women developed ALS.
The team classified veterans by branch of service (Army, Navy, Air Force, Marine Corps, Coast Guard or multiple branches), by rank (enlisted or officer), and by length of military careers. They then applied statistical models that adjusted for age, racial identity and Hispanic ethnicity, with separate analyses for men and women because occupational exposures can differ by sex.
Among men, the Army served as the baseline for comparison. Relative to Army veterans, those who served in the Air Force had a 29% higher ALS rate, Navy veterans 15% higher, and Coast Guard veterans 26% higher. By contrast, Marines showed a 22% lower rate of ALS compared with Army veterans. “The lower rate among the Marines was not so much a surprise in that it had been seen in many studies before, but those all had few Marines,” Weisskopf explained. “So seeing it in this much larger population really confirmed that finding and left that as a bit of a puzzle as to why they seem to be at lower risk.”
On the question of rank, officers carried a higher risk than enlisted personnel. Male officers had a 64% higher rate of ALS than their enlisted peers, while female officers were 72% more likely to develop ALS than female enlisted personnel. Differences between branches were most pronounced among younger veterans aged 17 to 61, with the disparities tending to lessen in older age groups. “The higher rate among officers was a bit of a surprise,” Weisskopf noted. “Because there are differences in ALS by branch and rank, it suggests that there is likely something specific to military experience. Given the higher risk among those in the Air Force, Navy, and Coast Guard, and officers we are considering how to probe those groups more specifically now.”
Despite these relative increases, the researchers emphasised that the absolute risk remains small for any individual. “It’s important to realise that ALS is still relatively rare. So any single person’s overall risk is small, even if elevated because of military service,” Weisskopf said. “Nonetheless, it is hugely impactful for those who get it, so we want to figure out why some people get it and some don’t so we can both try and prevent occurrences and also better understanding how it develops can give us insight into possible therapeutic avenues.”
The study also found that a longer length of military service was associated with lower ALS rates, a result that challenges the intuition that longer service equates to greater exposure. The authors offered several possible explanations: jobs with high exposure to risk factors might attract shorter service commitments; veterans who serve longer may be more likely to seek diagnoses outside veteran hospitals after leaving service, meaning their ALS cases might not appear in the Veterans Health Administration data. The higher risk observed in Air Force, Navy and Coast Guard veterans points to specific occupational hazards, such as jet fuel, aircraft exhaust or radiation, as potential contributors. Officers, who often have higher levels of education, may also reflect different risk profiles. Some prior studies have indicated that higher education correlates with a greater likelihood of ALS diagnosis, which could partly account for the observed differences.
The researchers cautioned that several limitations could influence the results. Rank information was unavailable for more than 900,000 male veterans, and the small number of ALS cases among women limited the ability to draw firm conclusions about branch differences in female veterans. They also lacked genetic data, though they noted that genetics alone is unlikely to explain the branch- and rank-specific patterns observed. They added that veterans’ access to healthcare, based on service-related disabilities or exposures, could bias results if those exposures also affect healthcare utilisation; to mitigate this, participants were required to have long-term health system data prior to diagnosis.
Looking ahead, the team aims to identify more precise occupational hazards tied to military experience. “We are trying to get more granular on the military experience than just branch and rank,” Weisskopf said. “It has turned out, though, to be much harder than we thought to link military service data (DOD) with post service health data (VA).”
The study, titled “Association of Military Branch and Rank With Amyotrophic Lateral Sclerosis Incidence Among United States Veterans,” was authored by Andrea L. Roberts, Alexandre D. Vilela Braga, Ian W. Tang, Ran S. Rotem, Lauren R. Moo, Donald R. Miller, Steven D. Shirk, and Marc G. Weisskopf.
