Exploring whether differences in brain diffusion MRI metrics distinguish symptom phenotypes in athletes exposed to repetitive head impacts.

It is important to account for the heterogeneity of clinical presentation when studying mild traumatic brain injury (mTBI) with advanced brain imaging. We used post-season symptom data from a cohort of rugby players exposed to repetitive head impacts, and we applied unsupervised learning to cluster athletes into clinically distinct groups. We explored whether these clusters demonstrated post-season group differences in white matter tracts compared to controls. This analysis framework suggests that group differences of diffusion metrics in athletes exposed to repetitive head impacts may be associated with clinical presentation rather than generalisable across all participants.