Structural Brain Differences in Professional Australian Rules Footballers Following Mild Traumatic Brain Injury: When Head Size Matters

Lee, Jackson MPardoe, Heath RParker, Donna MPedersen, MangorMakdissi, MichaelAbbott, David FJackson, Graeme DMito, Remika2026-02-042026-02-042026-01-16Frontiers in Neurology, ISSN: 1664-2295 (Print); 1664-2295 (Online), Frontiers Media SA, 17, 1701097-. doi: 10.3389/fneur.2026.17010971664-22951664-2295http://hdl.handle.net/10292/20585 Introduction Concussion, a type of mild traumatic brain injury common in collision sports, is thought to be associated with subtle brain changes that are not visually appreciable on conventional neuroimaging. This study quantified differences in subcortical volumes from structural MRI between 31 recently concussed professional Australian rules footballers (within 3 months of injury) and 37 healthy, non-athlete controls. Methods T1-weighted MRI were acquired at 3 T and processed using FreeSurfer. Hippocampal and amygdala volumes were normalized by estimated total intracranial volume (eTIV). Longitudinal changes were assessed in a subset of 12 footballers with follow-up MRI. Cortical thickness differences were also explored using vertex-wise analysis. Results Footballers exhibited lower proportional hippocampal and amygdala volumes, and reduced cortical thickness compared to controls. However, after exploring different methodological approaches for estimating intracranial volume (ICV), volumetric findings were seen to vary based on the ICV estimation method used for normalization. Discussion This study demonstrates subtle, likely persistent neuroanatomical differences between professional Australian rules footballers and non-athlete controls. Importantly, we advocate for cautious clinical interpretation of volumetric MRI findings considering methodological variabilities, particularly when inherent cohort differences (such as ICV) may bias results, and provide recommendations for future studies that examine volumetric changes in concussion cohorts. Copyright © 2026 Lee, Pardoe, Parker, Pedersen, Makdissi, Abbott, Jackson and Mito. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.5202 Biological Psychology52 PsychologyTraumatic Brain Injury (TBI)Basic Behavioral and Social ScienceBrain DisordersClinical ResearchPhysical Injury - Accidents and Adverse EffectsTraumatic Head and Spine InjuryBiomedical ImagingBehavioral and Social ScienceNeurosciencesNeurological1103 Clinical Sciences1109 Neurosciences1701 Psychology3202 Clinical sciences3209 Neurosciences5202 Biological psychologyStructural Brain Differences in Professional Australian Rules Footballers Following Mild Traumatic Brain Injury: When Head Size MattersJournal ArticleOpenAccess10.3389/fneur.2026.1701097