title: Imaging Correlates of Memory and Concussion History in Retired National Football League Athletes.
abstract: OBJECTIVE
  To our knowledge, this is the first study to show an association between concussion, cognition, and anatomical structural brain changes across the age spectrum in former National Football League athletes.
  
  
  OBJECTIVE
  To assess the relationship of hippocampal volume, memory performance, and the influence of concussion history in retired National Football League athletes with and without mild cognitive impairment (MCI).
  
  
  METHODS
  This retrospective cohort study assessed differences between groups, mean hippocampal volumes, and memory performance by computing age quintiles based on group-specific linear regression models corrected for multiple comparisons for both athletes and control participants. The study was conducted starting in November 2010 and is ongoing at a research center in the northern region of Texas. This current analysis was conducted from October 9, 2013, to August 21, 2014. Participants included 28 retired National Football League athletes, 8 of whom had MCI and a history of concussion, 21 cognitively healthy control participants, and 6 control participants with MCI without concussion.
  
  
  METHODS
  Hippocampal volume, age, California Verbal Learning Test scores, and the number of grade 3 (G3) concussions. In addition, the number of games played was examined as an objective variable pertaining to football history.
  
  
  RESULTS
  The mean (SD) age was 58.1 (13) years for the 28 former athletes and 59.0 (12) years for the 27 control participants. Retired athletes with concussion history but without cognitive impairment had normal but significantly lower California Verbal Learning Test scores compared with control participants (mean [SD], 52.5 [8] vs 60.24 [7]; P = .002); those with a concussion history and MCI performed worse (mean [SD], 37 [8.62]) compared with both control participants (P < .001) and athletes without memory impairment (P < .001). Among the athletes, 17 had a G3 concussion and 11 did not. Older retired athletes with at least 1 G3 concussion had significantly smaller bilateral hippocampal volumes compared with control participants at the 40th age percentile (left, P = .04; right, P = .03), 60th percentile (left, P = .009; right, P = .01), and 80th percentile (left, P = .001; right, P = .002) and a smaller right hippocampal volume compared with athletes without a G3 concussion at the 40th percentile (P = .03), 60th percentile (P = .02), and 80th percentile (P = .02). Athletes with a history of G3 concussion were more likely to have MCI (7 of 7) compared with retired athletes without a history of G3 concussion (1 of 5) older than 63 years (P = .01). In addition, the left hippocampal volume in retired athletes with MCI and concussion was significantly smaller compared with control participants with MCI (P = .03).
  
  
  CONCLUSIONS
  Prior concussion that results in loss of consciousness is a risk factor for increased hippocampal atrophy and the development of MCI. In individuals with MCI, hippocampal volume loss appears greater among those with a history of concussion.
authors.affiliation: Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas.
authors.forename: Jeremy F
authors.initials: JF
authors.lastname: Strain
authors.affiliation: Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas3Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas.
authors.forename: Kyle B
authors.initials: KB
authors.lastname: Womack
authors.affiliation: Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas.
authors.forename: Nyaz
authors.initials: N
authors.lastname: Didehbani
authors.affiliation: Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Spence
authors.affiliation: Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas.
authors.forename: Heather
authors.initials: H
authors.lastname: Conover
authors.affiliation: Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas2Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas3Department of Neurology and Neurotherapeutics, University of Texas.
authors.forename: John
authors.initials: J
authors.lastname: Hart
authors.affiliation: Center for BrainHealth, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas4Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kraut
authors.affiliation: Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas3Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas.
authors.forename: C Munro
authors.initials: CM
authors.lastname: Cullum
mesh_terms: D000328:Adult; D000368:Aged; D056352:Athletes / Q000523:psychology; D001924:Brain Concussion / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000209:etiology / Q000523:psychology; D015331:Cohort Studies; D005538:Football / Q000293:injuries* / Q000523:psychology; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology; D008875:Middle Aged; D009929:Organ Size; D012179:Retirement / Q000523:psychology; D012189:Retrospective Studies