Neurodegenerative mortality among National Football League Players.
Neurodegenerative mortality among National Football League Players.
Where did the research take place?
The study site has not been established. Author addresses may differ from where the research occurred.
Boston, US · Author affiliation
Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Boston, MA, USA.Location evidence
GB · Author affiliation · country only
Professional Footballers Association, England, UK.Location evidence
US · Author affiliation · country only
Department of Physical Medicine Rehabilitation and Anesthesiology, University of Missouri School of Medicine, Columbia, MO, USA.Location evidence
Framingham, US · Author affiliation
Framingham Heart Study, Boston University School of Medicine, Boston, MA, USA.Location evidence
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Original abstract
BACKGROUND: Empirical research demonstrates elevated neurodegenerative mortality among individuals with repetitive head impact (RHI) exposure, including National Football League (NFL) players. This investigation addressed prior methodological limitations, including selection bias, subjective diagnoses, and retrospective reporting, by analyzing the relationship between RHI exposure and neurodegenerative mortality in a fully enumerated, 5.8-fold larger cohort of NFL players. METHODS: A population-based retrospective cohort study was conducted comprising all current and former NFL athletes who debuted between 1960 and 2019 and played at least one regular or postseason NFL game, with National Death Index records (1979-2023) matched to Sports Reference, LLC data. Standardized mortality ratios (SMRs) were calculated from National Institute for Occupational Safety and Health data compared to an age-, sex-, race-, and calendar-year-standardized general population. Sensitivity analysis assessed whether the observed excess neurodegenerative mortality could be attributed to competing risks using a cause-specific hazard simulation. FINDINGS: A total of 19,824 athletes had a cumulative 518,833 person-years (mean = 26.2 years, SD = 16.2), with 1994 decedents. NFL players exhibited lower all-cause mortality (SMR = 0.70; 95% CI: 0.67-0.74) but higher neurodegenerative mortality (SMR = 3.94; 95% CI: 3.38-4.56), including amyotrophic lateral sclerosis (SMR = 4.55; 95% CI = 3.13-6.38), all-cause dementia (SMR = 3.80; 95% CI = 3.11-4.60), and Parkinson's disease (SMR = 3.88; 95% CI: 2.76-5.30). Cause-specific hazard simulation indicated that competing risks alone would inflate the expected NDD SMR by a factor of 1.30, yielding a residual neurodegenerative SMR of 3.04 (95% CI: 2.63-3.50). INTERPRETATION: Neurodegenerative mortality was nearly four times higher in NFL players compared to the general population and remained threefold higher after accounting for competing risks. Together, these findings strengthen the evidence for RHI exposure-related neurodegenerative mortality in NFL players that cannot be explained by differential survivorship. FUNDING: The National Institute of Neurological Disorders and Stroke [U54NS115266; U01NS086659], the National Institute on Aging [P30AG13846; P30AG072978], and the Maloney/Carpenter Trauma-Related Neurodegenerative Disease Research Fund.