Of 202 former football players who donated their brains for medical research, almost all had evidence of CTE.  All high school football players had mild pathology. 56 % of college players, 56% of semiprofessional players and 86% of professional players had major pathology.

Symptoms included: behavioral and mood changes, cognitive symptoms, and signs of dementia.

JAMA. 2017 Jul 25;318(4):360-370. doi: 10.1001/jama.2017.8334.

Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football.

Mez J¹, Daneshvar DH², Kiernan PT¹, Abdolmohammadi B¹, Alvarez VE³, Huber BR⁴, Alosco ML¹, Solomon TM⁵, Nowinski CJ⁶, McHale L⁷, Cormier KA¹, Kubilus CA¹, Martin BM⁸, Murphy L¹, Baugh CM⁹, Montenigro PH¹, Chaisson CE⁸, Tripodis Y¹⁰, Kowall NW¹¹, Weuve J¹², McClean MD¹³, Cantu RC¹⁴, Goldstein LE¹⁵, Katz DI¹⁶, Stern RA¹⁷, Stein TD¹⁸, McKee AC¹⁹.

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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 FootballLeague (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.