title: Neurological assessment and its relationship to CSF biomarkers in amateur boxers.
abstract: BACKGROUND
  Mild traumatic brain injury (TBI) or concussion is common in many sports. Today, neuropsychological evaluation is recommended in the monitoring of a concussion and in return-to-play considerations. To investigate the sensitivity of neuropsychological assessment, we tested amateur boxers post bout and compared with controls. Further the relationship between neuropsychological test results and brain injury biomarkers in the cerebrospinal fluid (CSF) were investigated.
  
  
  METHODS
  Thirty amateur boxers on high elite level with a minimum of 45 bouts and 25 non-boxing matched controls were included. Memory tests (Rey Osterrieth Complex Figure, Listening Span, Digit Span, Controlled Word Association Test, and computerized testing of episodic memory), tests of processing speed and executive functions (Trail Making, Reaction Time, and Finger Tapping) were performed and related to previously published CSF biomarker results for the axonal injury marker neurofilament light (NFL).
  
  
  RESULTS
  The neurological assessment showed no significant differences between boxers and controls, although elevated CSF NFL, as a sign of axonal injury, was detected in about 80% of the boxers 1-6 days post bout. The investigation of the relationship between neuropsychological evaluation and CSF NFL concentrations revealed that boxers with persisting NFL concentration elevation after at least 14 days resting time post bout, had a significantly poorer performance on Trail Making A (p = 0.041) and Simple Reaction Time (p = 0.042) compared to other boxers.
  
  
  CONCLUSIONS
  This is the first study showing traumatic axonal brain injury can be present without measureable cognitive impairment. The repetitive, subconcussive head trauma in amateur boxing causes axonal injury that can be detected with analysis of CSF NFL, but is not sufficient to produce impairment in memory tests, tests of processing speed, or executive functions. The association of prolonged CSF NFL increase in boxers with impairment of processing speed is an interesting observation, which needs to be verified in larger studies.
authors.affiliation: Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden; Institute for Clinical Sciences, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
authors.forename: Sanna
authors.initials: S
authors.lastname: Neselius
authors.affiliation: Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden; Institute for Clinical Sciences, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Brisby
authors.affiliation: Geriatric Section, University Hospital in Linköping, Linköping, Sweden; Institution of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Marcusson
authors.affiliation: Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden; Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; UCL Institute of Neurology, Queen Square, London, United Kingdom.
authors.forename: Henrik
authors.initials: H
authors.lastname: Zetterberg
authors.affiliation: Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden; Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
authors.forename: Kaj
authors.initials: K
authors.lastname: Blennow
authors.affiliation: Disability Research, Department of Behavioral Sciences and Learning, Linköping University, Linköping, Sweden; Linnaeus Centre HEAD, Linköping University, Linköping, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Karlsson
mesh_terms: D015415:Biomarkers / Q000134:cerebrospinal fluid*; D001914:Boxing; D006801:Humans; D016900:Neurofilament Proteins / Q000134:cerebrospinal fluid; D009483:Neuropsychological Tests; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D016900:Neurofilament Proteins; C044882:neurofilament protein L