Running head: CONCUSSION, HIT DATA AND NEUROPSYCHOLOGICAL OUTCOMES IN RUGBY 1 A dissertation submitted in partial fulfillment of the requirements for the award of the Degree of Master of Arts (Neuropsychology) Investigating history of concussion and data from head impact telemetry (xPatch) in relation to neuropsychological outcomes in a sample of adult rugby players in Cape Town Dale C. Stephen ACSENT Laboratory Department of Psychology University of Cape Town UniversitySeptember of 2016Cape Town Supervisor: Dr. Leigh Schrieff-Elson Co-Supervisors: A/Prof. Kevin Thomas and Prof. Anthony Figaji The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgement of the source. The thesis is to be used for private study or non- commercial research purposes only. Published by the University of Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. University of Cape Town CONCUSSION, HIT DATA AND NEUROPSYCHOLOGICAL OUTCOMES IN RUGBY 2 Author Note Dale C. Stephen, Department of Psychology, University of Cape Town; Leigh E. Schrieff-Elson, Department of Psychology, University of Cape Town; Kevin G. F. Thomas, Department of Psychology, University of Cape Town; Anthony Figaji, Division of Paediatric Neurosurgery, University of Cape Town. First, I would like to express many thanks to my supervisor, Dr Leigh Schrieff-Elson, for all her encouragement, assistance, guidance and feedback that without, this project would never have been undertaken. To A/Prof Kevin Thomas, thank you for always keeping your door open to me and always lending an ear, and for your advice on the dissertation. I would also like to pay a huge thank you and cheers to my family, my friends and Space Camp, and to Tish for being with me throughout this endeavour, and for your encouragement and unwavering support. A thank you must also go to Lydia Wepener for her help with data collection. This study could also not have been undertaken without the monetary funding from the National Research Foundation through the Master’s Freestanding Scholarship, and for this, thank you. CONCUSSION, HIT DATA AND NEUROPSYCHOLOGICAL OUTCOMES IN RUGBY 3 Table of Contents List of Figures ........................................................................................................................... 9 List of Tables .......................................................................................................................... 10 Abstract ................................................................................................................................... 11 Introduction ............................................................................................................................ 13 Classification and Diagnosis of Concussion ............................................................................ 15 Defining concussion. ............................................................................................................ 15 Subconcussive head injuries................................................................................................. 18 Epidemiology of Concussion ................................................................................................... 19 Concussion in rugby. ............................................................................................................ 20 Pathophysiology of Concussion ............................................................................................... 22 Neuropathology of Concussion................................................................................................ 23 Clinical Symptoms in the Acute Post-Concussion Phase ........................................................ 24 Assessment of clinical symptoms ........................................................................................ 27 Cognitive impairment in the acute post-concussion phase .................................................. 29 Association between cognitive outcomes and neuropathological consequences in the acute post-concussion phase ............................................................................................ 30 Investigating the course of cognitive recovery post- concussion with formal neuropsychological assessment ............................................................................................ 31 Persisting Neuropathological Consequences Associated with Recovery Post-Concussion .... 32 Persistent cognitive symptoms post-concussion .................................................................. 33 Possible reasons for inconsistencies ..................................................................................... 35 CONCUSSION, HIT DATA AND NEUROPSYCHOLOGICAL OUTCOMES IN RUGBY 4 Neuropsychological Effects of Multiple Concussions ............................................................. 36 The Neuropsychological Effects of Cumulative Subconcussive Head Injuries ...................... 39 Chronic Traumatic Encephalopathy (CTE) ............................................................................. 42 Measuring Concussive and Subconcussive Head Injuries using Head Impact Telemetry (HIT) .................................................................................................................................................. 43 Summary and Rationale ........................................................................................................ 46 Study 1: Investigating the relationship between cognitive performance and concussion history in a sample of rugby players and non-contact sports players ............................... 48 Aims and Hypothesis ............................................................................................................... 49 Methods.................................................................................................................................... 50 Design and setting ................................................................................................................ 50 Participants ........................................................................................................................... 50 Exclusion criteria. ............................................................................................................ 52 Materials. .............................................................................................................................. 53 Screening measures. ......................................................................................................... 53 Symptom and cognitive testing measures ......................................................................... 55 Procedure .............................................................................................................................. 57 Data analysis ........................................................................................................................ 58 Sample characteristics ...................................................................................................... 58 Effect of concussion history on cognitive performance. ................................................... 58 Ethical considerations .......................................................................................................... 60 Informed consent .............................................................................................................. 60 CONCUSSION, HIT DATA AND NEUROPSYCHOLOGICAL OUTCOMES IN RUGBY 5 Confidentiality .................................................................................................................. 61 Referrals ........................................................................................................................... 61 Debriefing ......................................................................................................................... 61 Risks and benefits ............................................................................................................. 61 Results ...................................................................................................................................... 62 Between-groups analysis: Participant characteristics .......................................................... 62 Between-groups analysis: Cognitive outcomes ................................................................... 65 Correlational analyses: Cognitive outcomes and indicators of a history of concussion severity ................................................................................................................................. 66 Discussion ................................................................................................................................ 67 Summary of results............................................................................................................... 68 Limitations and future directions ......................................................................................... 74 Conclusion ............................................................................................................................ 75 Study 2: A novel method investigating the use of the xPatch (X2Biosystems Inc.), a means of head impact telemetry (HIT), to determine the number of subconcussive head injuries in a sample of university rugby players ................................................................