New Study Finds Pro Football Athletes Have Four Times Higher Mortality from ALS
Association between longer career and increased risk adds to growing evidence that playing professional football may cause neurodegenerative disease
BOSTON – Professional football players may be four times more likely to die from amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease) compared to the general population, according to the findings of a new study led by researchers from the Department of Physical Medicine and Rehabilitation at Harvard Medical School-affiliated Spaulding Rehabilitation and the Boston University CTE Center.
The study, published in JAMA Network Open, is titled "Incidence of and Mortality from Amyotrophic Lateral Sclerosis in National Football League Athletes."
The research also revealed, for the first time, an association between longer professional careers and an increased risk of ALS, with players who developed ALS playing an average of 7.0 seasons, 56% longer than matched professional football athletes without ALS, who averaged 4.5 years of play.
“ALS is a progressive and fatal disease, where 90% of cases have an unknown cause,” said Daniel Daneshvar, MD, PhD, assistant professor at Harvard Medical School and a brain injury physician at Spaulding Rehabilitation Hospital. “We believe this novel finding linking a longer career to increased risk of ALS adds to the growing evidence that repetitive head impacts from playing football are contributing to professional players developing ALS.”
Steve McMichael, a fifteen-year professional player, two-time All-Pro defensive tackle, and member of the iconic 1985 Chicago Bears, was the most recent player diagnosed with ALS in the study. “I thank the doctors for providing new insight to potentially explain why my body no longer works,” McMichael said. “If playing football is responsible for the ALS in three out of every four of us, I hope this inspires additional research that focuses on how to help us.”
This study represents the most comprehensive investigation of ALS in American-style professional football players to date. The study included 19,423 players, including every player that debuted between 1960 and 2019. ALS diagnoses were obtained from news reports and obituaries, and validated against National Death Index results where available. The study was also the first to investigate ALS incidence by including living players with ALS in the analysis and found that professional players are 3.6 times more likely to develop ALS than the general population.
“In our brain bank, we have found a similar relationship between a longer football career and an increased risk of other neurodegenerative diseases, including chronic traumatic encephalopathy (CTE) and Lewy body disease, which can cause parkinsonism,” said Ann McKee, MD, chief of neuropathology at VA Boston Healthcare System and director of the BU CTE Center. “It has become clear that years of repeated impacts to the head can cause the human brain to break down along many pathways.”
Secondary analyses matched pro football athletes with ALS to athletes without ALS, based on debut year to account for differences in age, era of play, and racial composition of the professional football leagues over time.
“The observed increase in ALS cases is remarkable, but may actually underestimate the true rate of ALS in professional football players,” Daneshvar said. “Because athletes with ALS were identified based on news reports or obituaries, if there were athletes who did not publicize their ALS status during life or at death, these athletes would not have been included in this study.”
To test if athlete fame was associated with the ability to identify whether an athlete has ALS, the study examined whether factors related to fame were different between professional football players with ALS and professional football players without ALS, and found no differences. Although factors like pesticide exposure, or body mass index (BMI) have been implicated in ALS risk, there was no relationship between where athletes were born, or their BMI at professional debut, and ALS risk.
The study was supported by grants and funding from the National Institutes of Health, Department of Veterans Affairs, Department of Defense, Canadian Institutes of Health Research, Fonds de Recherche du Quebec-Sante, the Alzheimer’s Association, the Nick and Lynn Buoniconti Foundation, the Concussion Legacy Foundation, the Adlinger Foundation, World Wrestling Entertainment Inc., Amylyx Therapeutics, Revalesio Corporation, UCB/Ra Pharmaceuticals, Biohaven Pharmaceuticals, Clene Nanomedicine, Prilenia Therapeutics, Seelos Therapeutics, The ALS Association, the American Academy of Neurology, ALS Finding a Cure, the Saleh Foundation, the Spastic Paraplegia Foundation, and the Muscular Dystrophy Association.
About Spaulding Rehabilitation Network
A member of the Mass General Brigham Health System, the Spaulding Rehabilitation Network includes Spaulding Rehabilitation Hospital, with a main campus in Charlestown the 3rdd ranked rehabilitation hospital in the country by U.S. News & World Report, along with Spaulding Rehabilitation Hospital Cape Cod, Spaulding Hospital Cambridge, Spaulding Nursing and Therapy Center Brighton, and over 25 outpatient sites throughout Eastern Massachusetts. An acclaimed teaching hospital of Harvard Medical School and home to the Department of Physical Medicine and Rehabilitation, Spaulding is recognized as the top residency program in the U.S. in the 2020/2021 Doximity Residency Navigator. Spaulding also was recognized by the 2021 Disability Equality Index as a “Best Places to Work for Disability Inclusion.” For more information, visit www.spauldingrehab.org.
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