To identify fluid biomarkers and brain imaging features associated with sport-related mild traumatic brain injury (mTBI).

The current approach to mTBI evaluation is heavily reliant upon symptom reporting and there is a need for objective tools to aid the process.

A prospective study of 220 active rugby players. We obtained baseline and post-mTBI plasma samples as well as neuro-psychometric assessments. Post-match players without mTBI were sampled as controls. Glial fibrillary acidic protein (GFAP), Neurofilament light (NF-L) and tau were measured using ultrasensitive single molecule array technology, the Simoa Human Neurology 4-Plex A assay. A subset of players (non-injured N=18 & post MTBI, N=10) underwent MRI brain imaging, including T1-volumetric, 99-direction multishell diffusion weighted and susceptibility weighted imaging (SWI). Non-rugby playing participants (N=32) were scanned as controls. Diffusion weighted images were pre-processed following the DTIFIT pipeline and fractional anisotropy (FA) values extracted.

We observed post-match elevations in NF-L, tau and GFAP. Tau was elevated in both post-match controls and post-match mTBI players, whereas NF-L and GFAP appeared to be specific for mTBI. NF-L and GFAP were elevated when measured between 1 hour and 10 days post injury. The presence of microbleeds on SWI were detected in 2/10 acute mTBI players and none in the controls. Mean FA showed significantly reduced FA within the right corticospinal tract across all rugby players.

GFAP and NF-L show potential as objective markers of brain injury in sport-related mTBI. The imaging results indicate that there may be effects of repetitive collisions on white matter integrity.