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Original Investigation
July 25, 2017

Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football

Author Affiliations
  • 1Boston University Alzheimer’s Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts
  • 2Department of Neurology, Boston University School of Medicine, Boston, Massachusetts
  • 3Department of Orthopaedic Surgery, Stanford University, Stanford, California
  • 4VA Boston Healthcare System, US Department of Veteran Affairs, Boston, Massachusetts
  • 5Department of Veterans Affairs Medical Center, Bedford, Massachusetts
  • 6Concussion Legacy Foundation, Waltham, Massachusetts
  • 7Data Coordinating Center, Boston University School of Public Health, Boston, Massachusetts
  • 8Interfaculty Initiative in Health Policy, Harvard University, Boston, Massachusetts
  • 9Division of Sports Medicine, Boston Children’s Hospital, Boston, Massachusetts
  • 10Department of Biostatistics, Boston University, Boston, Massachusetts
  • 11School of Public Health, Boston University, Boston, Massachusetts
  • 12Department of Pathology, Boston University School of Medicine, Boston, Massachusetts
  • 13Department of Epidemiology, Boston University, Boston, Massachusetts
  • 14Department of Environmental Health, Boston University, Boston, Massachusetts
  • 15Department of Neurosurgery, Emerson Hospital, Concord, Massachusetts
  • 16Department of Psychiatry, Boston University School of Medicine, Boston, Massachusetts
  • 17Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts
  • 18Department of Biomedical Engineering, Boston University College of Engineering, Boston, Massachusetts
  • 19Department of Electrical and Computer Engineering, Boston University College of Engineering, Boston, Massachusetts
  • 20Braintree Rehabilitation Hospital, Braintree, Massachusetts
  • 21Department of Neurosurgery, Boston University School of Medicine, Boston, Massachusetts
  • 22Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts
  • 23Boston University School of Medicine, Boston, Massachusetts
JAMA. 2017;318(4):360-370. doi:10.1001/jama.2017.8334
Key Points

Question  What are the neuropathological and clinical features of a case series of deceased players of American football neuropathologically diagnosed as having chronic traumatic encephalopathy (CTE)?

Findings  In a convenience sample of 202 deceased players of American football from a brain donation program, CTE was neuropathologically diagnosed in 177 players across all levels of play (87%), including 110 of 111 former National Football League players (99%).

Meaning  In a convenience sample of deceased players of American football, a high proportion showed pathological evidence of CTE, suggesting that CTE may be related to prior participation in football.

Abstract

Importance  Players of American football may be at increased risk of long-term neurological conditions, particularly chronic traumatic encephalopathy (CTE).

Objective  To determine the neuropathological and clinical features of deceased football players with CTE.

Design, Setting, and Participants  Case series of 202 football players whose brains were donated for research. Neuropathological evaluations and retrospective telephone clinical assessments (including head trauma history) with informants were performed blinded. Online questionnaires ascertained athletic and military history.

Exposures  Participation in American football at any level of play.

Main Outcomes and Measures  Neuropathological diagnoses of neurodegenerative diseases, including CTE, based on defined diagnostic criteria; CTE neuropathological severity (stages I to IV or dichotomized into mild [stages I and II] and severe [stages III and IV]); informant-reported athletic history and, for players who died in 2014 or later, clinical presentation, including behavior, mood, and cognitive symptoms and dementia.

Results  Among 202 deceased former football players (median age at death, 66 years [interquartile range, 47-76 years]), CTE was neuropathologically diagnosed in 177 players (87%; median age at death, 67 years [interquartile range, 52-77 years]; mean years of football participation, 15.1 [SD, 5.2]), including 0 of 2 pre–high school, 3 of 14 high school (21%), 48 of 53 college (91%), 9 of 14 semiprofessional (64%), 7 of 8 Canadian Football League (88%), and 110 of 111 National Football League (99%) players. Neuropathological severity of CTE was distributed across the highest level of play, with all 3 former high school players having mild pathology and the majority of former college (27 [56%]), semiprofessional (5 [56%]), and professional (101 [86%]) players having severe pathology. Among 27 participants with mild CTE pathology, 26 (96%) had behavioral or mood symptoms or both, 23 (85%) had cognitive symptoms, and 9 (33%) had signs of dementia. Among 84 participants with severe CTE pathology, 75 (89%) had behavioral or mood symptoms or both, 80 (95%) had cognitive symptoms, and 71 (85%) had signs of dementia.

Conclusions and Relevance  In a convenience sample of deceased football players who donated their brains for research, a high proportion had neuropathological evidence of CTE, suggesting that CTE may be related to prior participation in football.

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