title: Effects of heading exposure and previous concussions on neuropsychological performance among Norwegian elite footballers.
abstract: BACKGROUND
  Cross-sectional studies have indicated that neurocognitive performance may be impaired among football players. Heading the ball has been suggested as the cause, but recent reviews state that the reported deficits are more likely to be the result of head injuries.
  
  
  OBJECTIVE
  To examine the association between previous concussions and heading exposure with performance on computer based neuropsychological tests among professional Norwegian football players.
  
  
  METHODS
  Players in the Norwegian professional football league (Tippeligaen) performed two consecutive baseline neuropsychological tests (Cogsport) before the 2004 season (90.3% participation, n = 271) and completed a questionnaire assessing previous concussions, match heading exposure (self-reported number of heading actions per match), player career, etc. Heading actions for 18 players observed in two to four matches were counted and correlated with their self-reported values.
  
  
  RESULTS
  Neither match nor lifetime heading exposure was associated with neuropsychological test performance. Nineteen players scored below the 95% confidence interval for one or more subtasks, but they did not differ from the rest regarding the number of previous concussions or lifetime or match heading exposure. The number of previous concussions was positively associated with lifetime heading exposure (exponent (B) = 1.97(1.03-3.75), p = 0.039), but there was no relation between previous concussions and test performance. Self-reported number of headings correlated well with the observed values (Spearman's rho = 0.77, p < 0.001).
  
  
  CONCLUSIONS
  Computerised neuropsychological testing revealed no evidence of neuropsychological impairment due to heading exposure or previous concussions in a cohort of Norwegian professional football players.
authors.affiliation: Oslo Sports Trauma and Research Center, Oslo, Norway. truls.straume-nesheim@nih.no
authors.forename: T M
authors.initials: TM
authors.lastname: Straume-Naesheim
authors.forename: T E
authors.initials: TE
authors.lastname: Andersen
authors.forename: J
authors.initials: J
authors.lastname: Dvorak
authors.forename: R
authors.initials: R
authors.lastname: Bahr
mesh_terms: D000328:Adult; D001924:Brain Concussion / Q000150:complications* / Q000503:physiopathology; D003072:Cognition Disorders / Q000209:etiology* / Q000503:physiopathology; D015331:Cohort Studies; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D019416:Head Movements / Q000502:physiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology; D012916:Soccer / Q000293:injuries*; D011795:Surveys and Questionnaires