Behavioural outcomes and neuropathology associated with mild traumatic brain injury

Abstract

Mild traumatic brain injury (mTBI) is an injury to the head caused by external force or blunt trauma that leads to an alteration in consciousness; loss of consciousness of less than 30 minutes and post-traumatic amnesia of less than 24 hours may be present. Previous studies have suggested there is an association between mTBI sustained in youth and risk behaviours. Additionally, MRI techniques that assess brain microstructure have been shown to be sensitive to the neuropathology of mTBI.
I carried out a systematic review to explore the association between mTBI in youth and later risk behaviour. This highlighted a paucity of good quality longitudinal evidence. I then conducted a study investigating the same association using data from ALSPAC, a large longitudinal birth cohort. I included a negative exposure control group of participants with orthopaedic injury (OI) to uncover potentially unmeasured confounding factors. Using logistic and ordinal regression on outcomes related to substance use, crime and psychiatric symptoms, I found causal evidence for an association between mTBI and hazardous alcohol use.
Next, I explored the association between mTBI and four MRI-based measures of the cortex in a subsample of ALSPAC participants. Unexpectedly, OI was associated with higher values for some of the measures, suggesting a potential bias in the data. Finally, I carried out a diffusion tensor imaging study on rugby players who had recently sustained a sport-related mTBI and found indications of possible oedema or axonal injury in the recently injured group. This study was limited by a small sample size and wide range of time post-injury, however.
My findings highlight the importance of providing support to young people following mTBI and continued consideration of mTBI in high-contact sports. Future research should explore the link between mTBI, alcohol use and neuropathology using longitudinal research, negative control design and multiple MRI methods.

Date of Award	19 Mar 2019
Original language	English
Awarding Institution	University of Bristol
Supervisor	Marcus R Munafo (Supervisor)