title: Persistent, long-term cerebral white matter changes after sports-related repetitive head impacts.
abstract: BACKGROUND
  Repetitive head impacts (RHI) sustained in contact sports are thought to be necessary for the long-term development of chronic traumatic encephalopathy (CTE). Our objectives were to: 1) characterize the magnitude and persistence of RHI-induced white matter (WM) changes; 2) determine their relationship to kinematic measures of RHI; and 3) explore their clinical relevance.
  
  
  METHODS
  Prospective, observational study of 10 Division III college football players and 5 non-athlete controls during the 2011-12 season. All subjects underwent diffusion tensor imaging (DTI), physiologic, cognitive, and balance testing at pre-season (Time 1), post-season (Time 2), and after 6-months of no-contact rest (Time 3). Head impact measures were recorded using helmet-mounted accelerometers. The percentage of whole-brain WM voxels with significant changes in fractional anisotropy (FA) and mean diffusivity (MD) from Time 1 to 2, and Time 1 to 3 was determined for each subject and correlated to head impacts and clinical measures.
  
  
  RESULTS
  Total head impacts for the season ranged from 431-1,850. No athlete suffered a clinically evident concussion. Compared to controls, athletes experienced greater changes in FA and MD from Time 1 to 2 as well as Time 1 to 3; most differences at Time 2 persisted to Time 3. Among athletes, the percentage of voxels with decreased FA from Time 1 to 2 was positively correlated with several helmet impact measures. The persistence of WM changes from Time 1 to 3 was also associated with changes in serum ApoA1 and S100B autoantibodies. WM changes were not consistently associated with cognition or balance.
  
  
  CONCLUSIONS
  A single football season of RHIs without clinically-evident concussion resulted in WM changes that correlated with multiple helmet impact measures and persisted following 6 months of no-contact rest. This lack of WM recovery could potentially contribute to cumulative WM changes with subsequent RHI exposures.
authors.affiliation: Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Bazarian
authors.affiliation: Imaging Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Imaging Sciences, Biomedical Engineering, and Physics, University of Rochester, Rochester, New York, United States of America.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, United States of America.
authors.forename: Damir
authors.initials: D
authors.lastname: Janigro
authors.affiliation: Athletics and Recreation, University of Rochester, Rochester, New York, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Rozen
authors.affiliation: University of Rochester, Rochester, New York, United States of America.
authors.forename: Andrew
authors.initials: A
authors.lastname: Roberts
authors.affiliation: Hamilton College, Clinton, New York, United States of America.
authors.forename: Hannah
authors.initials: H
authors.lastname: Javien
authors.affiliation: Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.
authors.forename: Kian
authors.initials: K
authors.lastname: Merchant-Borna
authors.affiliation: Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.
authors.forename: Beau
authors.initials: B
authors.lastname: Abar
authors.affiliation: Physics and Astronomy, University of Rochester, Rochester, New York, United States of America.
authors.forename: Eric G
authors.initials: EG
authors.lastname: Blackman
mesh_terms: D056352:Athletes; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology; D001924:Brain Concussion / Q000175:diagnosis / Q000503:physiopathology; D006259:Craniocerebral Trauma / Q000175:diagnosis / Q000503:physiopathology*; D056324:Diffusion Tensor Imaging; D005538:Football / Q000293:injuries*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011859:Radiography; D013997:Time Factors; D014495:Universities; D066127:White Matter / Q000503:physiopathology*; D055815:Young Adult
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