title: Association between concussion and mental health in former collegiate athletes.
abstract: BACKGROUND
  The existing research on the association between concussion and mental health outcomes is largely limited to former professional athletes. This cross-sectional study estimated the association between recurrent concussion and depression, impulsivity, and aggression in former collegiate athletes.
  
  
  METHODS
  Former collegiate athletes who played between 1987-2012 at a Division I university completed an online questionnaire. The main exposure, total number of self-recalled concussions (sport-related and non-sport-related), were categorized as: zero (referent), one, two, or three or more concussions. The main outcomes were the depression module of The Patient Health Questionnaire (PHQ-9), the Short Form of the Barratt Impulsiveness scale (BIS15); and the 12-item Short Form of the Buss-Perry Aggression Questionnaire (BPAQ-SF). Depression was categorized into a binomial severity classification that differentiated between no or mild depression (PHQ-9 scores <10) and moderate to severe depression (PHQ-9 scores ≥10). Impulsivity and aggression were kept as continuous outcomes. Binomial regression estimated adjusted prevalence ratios (PR). Linear regression estimated adjusted mean differences (MD).
  
  
  RESULTS
  Of the 797 respondents with complete data (21.9% completion rate), 38.8% reported at least one concussion. Controlling for alcohol dependence and family history of depression, the prevalence of moderate to severe depression among former collegiate athletes reporting three or more concussions in total was 2.4 times that of those reporting zero concussions [95% Confidence Interval (CI): 1.0, 5.7]. Controlling for alcohol dependence, family history of anxiety, relationship status, obtaining a post-graduate degree, and playing primary college sport professionally, former collegiate athletes reporting two or more concussions in total had higher mean scores for impulsivity, compared to those reporting no concussions (2 concussions MD = 2.7; 95% CI: 1.2, 4.1; 3+ concussions MD = 1.9; 95% CI: 0.6, 3.2). Controlling for alcohol dependence, sex, and relationship status, former collegiate athletes reporting three or more concussions in total had a higher mean score for aggression, compared to those reporting no concussions (MD = 3.0; 95% CI: 1.4, 4.7).
  
  
  CONCLUSIONS
  Our study found an association between former concussion and greater risk of severe depression and higher levels of impulsivity and aggression among former collegiate athletes. Additional prospective studies better addressing causality and ascertaining valid lifetime concussion histories and medical histories are needed.
authors.affiliation: Department of Epidemiology, Injury Prevention Research Center, University of North Carolina at Chapel Hill, Bank of America Building, Suite 500, 137 E. Franklin St, Chapel Hill, 27599-7505, NC, USA. zkerr@datalyscenter.org.|NCAA Injury Surveillance Program, Datalys Center for Sports Injury Research and Prevention, 401 West Michigan Street, Suite 500, Indianapolis, 46202, IN, USA. zkerr@datalyscenter.org.
authors.forename: Zachary Y
authors.initials: ZY
authors.lastname: Kerr
authors.affiliation: University of North Carolina at Chapel Hill, Bank of America Building, Suite 306, 137 E. Franklin St, Chapel Hill, NC, USA.
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Evenson
authors.affiliation: University of North Carolina at Chapel Hill, Bank of America Building, Suite 306, 137 E. Franklin St, Chapel Hill, NC, USA.
authors.forename: Wayne D
authors.initials: WD
authors.lastname: Rosamond
authors.affiliation: Department of Exercise and Sport Science, Matthew A. Gfeller Sport-related Traumatic Brain Injury Research Center, 313 Woollen Gymnasium, Chapel Hill, 27599-8605, NC, USA.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Mihalik
authors.affiliation: Department of Exercise and Sport Science, Matthew A. Gfeller Sport-related Traumatic Brain Injury Research Center, 2207 Stallings-Evans Sports Medicine Center, Chapel Hill, 27599-8700, NC, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Guskiewicz
authors.affiliation: Department of Epidemiology, Injury Prevention Research Center, University of North Carolina at Chapel Hill, Bank of America Building, Suite 500, 137 E. Franklin St, Chapel Hill, 27599-7505, NC, USA.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Marshall
keywords: Aggression; Depression; Epidemiology; Impulsivity; Injury; Traumatic brain injury