Amyotrophic Lateral Sclerosis Risk Tied to NFL Play Duration in Athletes

National Football League (NFL) players’ risk of incidence and mortality from amyotrophic lateral sclerosis (ALS) is nearly 4 times that of other populations, according to a study published in JAMA Network Open.

The cause of ALS, a fatal disease that involves loss of upper and lower motor neurons, considered sporadic, is unknown, although incidence tends to be higher among older adults, men, and White individuals. Prior research has indicated individuals with higher body mass index (BMI) have a lower risk of developing ALS decades later while environmental toxins and strenuous exercise have been associated with the disease. The researchers of the current study sought to expand upon research of ALS among NFL players who played for at least 5 years, which exceeds the mean 3.3 years of an NFL player’s career.

This is the largest study of ALS risk in NFL athletes and the first to report ALS incidence in NFL athletes, according to the researchers.

Researchers included data of 19,423 former and current NFL players (age range 23 to 78) from Hidden Game Sports/24-7 Baseball LLC. They excluded athletes drafted before 1960 or after 2019 and those who played less than 1 regular season game professionally. Follow-up was conducted for 30.6±13.7 years.

Thirty-eight NFL players with ALS were part of the cohort and were diagnosed at 51.0±13.8 years. Those who died during the study window with ALS as an underlying entity or cause of death (n=22) had lived with the disease for 3.5±2.6 and had been diagnosed at 52.5±13.8 years. Those (n=10) who lived had been diagnosed with ALS at 46.1±12.6 years and had lived with ALS for 6.1±5.7 years. The researchers calculated the standardized incidence ratio was 3.59 and the standardized mortality ratio was 3.94.

For a nested case-control study, the researchers utilized a cumulative incidence sampling design to match 5 randomly selected NFL athletes without ALS to each athlete with ALS from the same debut year.

They found athletes with ALS played longer in the NFL (7.0±3.9 years) compared with matched athletes without ALS (4.5±3.6 years OR 1.2 P ≤.001). ALS was associated with duration of NFL play and debut year. ALS was not associated with birthplace, position played, or BMI.

Study limitations included reliance on public records to identify cases, inability to assess clinical differences or other risk factors, limited sample of athletes with ALS, lack of data regarding RHI exposure and traumatic brain injury (TBI) history.

“Athletes with a diagnosis of ALS had longer NFL careers than those without ALS, suggesting an association between NFL duration of play and ALS,” the researchers stated. “The identification of these risk factors for ALS helps to inform the study of pathophysiological mechanisms responsible for this fatal neurodegenerative disease.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. This research was supported by World Wrestling Entertainment, Inc., Amylyx Therapeutics, Revalesio Corporation, UCB/Ra Pharmaceuticals, Biohaven Pharmaceuticals, Clene Nanomedicine, Prilenia Therapeutics, and Seelos Therapueutics.  Please see the original reference for a full list of authors’ disclosures. 

Reference

Daneshvar DH, Mez J, Alosco ML, et al. Incidence of and mortality from amyotrophic lateral sclerosis in National Football League athletes. JAMA Network Open. Published online December 15, 2021. doi: 10.1001/jamanetworkopen.2021.38801