title: A Comparison of Cognitive Function in Former Rugby Union Players Compared with Former Non-Contact-Sport Players and the Impact of Concussion History.
abstract: OBJECTIVE
  This study investigated differences in cognitive function between former rugby and non-contact-sport players, and assessed the association between concussion history and cognitive function.
  
  
  METHODS
  Overall, 366 former players (mean ± standard deviation [SD] age 43.3 ± 8.2 years) were recruited from October 2012 to April 2014. Engagement in sport, general health, sports injuries and concussion history, and demographic information were obtained from an online self-report questionnaire. Cognitive functioning was assessed using the online CNS Vital Signs neuropsychological test battery. Cohen's d effect size statistics were calculated for comparisons across player groups, concussion groups (one or more self-reported concussions versus no concussions) and between those groups with CNS Vital Signs age-matched norms (US norms). Individual differences within groups were represented as SDs.
  
  
  RESULTS
  The elite-rugby group (n = 103) performed worse on tests of complex attention, processing speed, executive functioning, and cognitive flexibility than the non-contact-sport group (n = 65), and worse than the community-rugby group (n = 193) on complex attention. The community-rugby group performed worse than the non-contact group on executive functioning and cognitive flexibility. Compared with US norms, all three former player groups performed worse on verbal memory and reaction time; rugby groups performed worse on processing speed, cognitive flexibility and executive functioning; and the community-rugby group performed worse on composite memory. The community-rugby group and non-contact-sport group performed slightly better than US norms on complex attention, as did the elite-rugby group for motor speed. All three player groups had greater individual differences than US norms on composite memory, verbal memory and reaction time. The elite-rugby group had greater individual differences on processing speed and complex attention, and the community-rugby group had greater individual differences on psychomotor speed and motor speed. The average number of concussions recalled per player was greater for elite rugby and community rugby than non-contact sport. Former players who recalled one or more concussions (elite rugby, 85 %; community rugby, 77 %; non-contact sport, 23 %) had worse scores on cognitive flexibility, executive functioning, and complex attention than players who did not recall experiencing a concussion.
  
  
  CONCLUSIONS
  Past participation in rugby or a history of concussion were associated with small to moderate neurocognitive deficits (as indicated by worse CNS Vital Signs scores) in athletes post retirement from competitive sport.
authors: Faculty of Health and Environmental Sciences, Sports Performance Research Institute New Zealand, Auckland University of Technology, Private Bag 92006, Auckland, 1142, New Zealand. patria.hume@aut.ac.nz.
authors: Patria A
authors: PA
authors: Hume
authors: National Institute for Stroke and Applied Neurosciences, Auckland University of Technology, Auckland, New Zealand.
authors: Alice
authors: A
authors: Theadom
authors: Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand.
authors: Gwyn N
authors: GN
authors: Lewis
authors: New Zealand Rugby, Wellington, New Zealand.
authors: Kenneth L
authors: KL
authors: Quarrie
authors: Faculty of Health and Environmental Sciences, Sports Performance Research Institute New Zealand, Auckland University of Technology, Private Bag 92006, Auckland, 1142, New Zealand.
authors: Scott R
authors: SR
authors: Brown
authors: Department of Neurology, Auckland City Hospital, Auckland, New Zealand.
authors: Rosamund
authors: R
authors: Hill
authors: University of North Carolina Injury Prevention Research Centre, Chapel Hill, NC, USA.
authors: Stephen W
authors: SW
authors: Marshall
mesh_terms: D000328:Adult; D001265:Athletic Injuries; D001924:Brain Concussion / Q000175:diagnosis* / Q000523:psychology; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D005538:Football / Q000293:injuries; D006801:Humans; D008875:Middle Aged; D009483:Neuropsychological Tests; D009520:New Zealand