title: Soccer heading is associated with white matter microstructural and cognitive abnormalities.
abstract: OBJECTIVE
  To investigate the association of soccer heading with subclinical evidence of traumatic brain injury.
  
  
  METHODS
  With institutional review board approval and compliance with HIPAA guidelines, 37 amateur soccer players (mean age, 30.9 years; 78% [29] men, 22% [eight] women) gave written informed consent and completed a questionnaire to quantify heading in the prior 12 months and lifetime concussions. Diffusion-tensor magnetic resonance (MR) imaging at 3.0 T was performed (32 directions; b value, 800 sec/mm(2); 2 × 2 × 2-mm voxels). Cognitive function was measured by using a computerized battery of tests. Voxelwise linear regression (heading vs fractional anisotropy [FA]) was applied to identify significant regional associations. FA at each location and cognition were tested for a nonlinear relationship to heading by using an inverse logit model that incorporated demographic covariates and history of concussion.
  
  
  RESULTS
  Participants had headed 32-5400 times (median, 432 times) over the previous year. Heading was associated with lower FA at three locations in temporo-occipital white matter with a threshold that varied according to location (885-1550 headings per year) (P < .00001). Lower levels of FA were also associated with poorer memory scores (P < .00001), with a threshold of 1800 headings per year. Lifetime concussion history and demographic features were not significantly associated with either FA or cognitive performance.
  
  
  CONCLUSIONS
  Heading is associated with abnormal white matter microstructure and with poorer neurocognitive performance. This relationship is not explained by a history of concussion.
authors.affiliation: Gruss Magnetic Resonance Research Center, Department of Radiology, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Ave, Bronx, NY 10461, USA. michael.lipton@einstein.yu.edu
authors.forename: Michael L
authors.initials: ML
authors.lastname: Lipton
authors.forename: Namhee
authors.initials: N
authors.lastname: Kim
authors.forename: Molly E
authors.initials: ME
authors.lastname: Zimmerman
authors.forename: Mimi
authors.initials: M
authors.lastname: Kim
authors.forename: Walter F
authors.initials: WF
authors.lastname: Stewart
authors.forename: Craig A
authors.initials: CA
authors.lastname: Branch
authors.forename: Richard B
authors.initials: RB
authors.lastname: Lipton
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000473:pathology*; D003072:Cognition Disorders / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012916:Soccer / Q000293:injuries*; D014949:Wounds, Nonpenetrating / Q000473:pathology*