Author(s): HONDA, Y., ARAMAKI, Y., Institution: CHUKYO UNIVERSITY, Country: JAPAN, Abstract-ID: 1923

INTRODUCTION:
American football involves frequent physical contact and high cognitive demands, both of which may influence players’ cortical gray matter in opposing ways: neurodegeneration and neuroplasticity. For example, repetitive head impacts have been associated with cortical gray matter volume loss. However, most previous studies have focused on players with more than 10 years of experience, leaving gray matter changes during the early stages of football participation poorly understood. In contrast, the complex visuospatial and cognitive demands of sports may promote neuroplastic increases in gray matter volume, but evidence for such adaptations in American football players remains limited. Japanese collegiate players, who typically begin playing football at the university level, provide a unique opportunity to investigate these neurodegenerative and neuroplastic processes during the early phase of football exposure.
METHODS:
We conducted a two-year longitudinal magnetic resonance imaging study of 15 male collegiate football players in Japan (age range, 18.7–20.5 years), all with ≤7 years of football experience. T1-weighted images were acquired twice and analyzed using voxel-based morphometry to evaluate longitudinal changes in cortical gray matter volume potentially reflecting neurodegenerative processes and use-dependent neuroplasticity. The significance level was set at p < 0.05 (family-wise error corrected: FWE-corrected).
RESULTS:
Two years of football exposure was associated with significant gray matter volume reductions in the dorsal frontal cortex (p[FWE-corrected] < 0.05), a region implicated in movement switching and inhibition, whereas no significant subcortical volume changes were detected. In contrast, significant gray matter volume enlargements were observed in the parietal and occipital cortices corresponding to the dorsal visual stream (p[FWE-corrected] < 0.05), which is critical for visuospatial cognition and interaction with dynamic environments.
CONCLUSION:
Leveraging the unique characteristics of Japanese collegiate athletes, this study provides novel insights into early-stage structural brain changes in football players, suggesting two opposing processes: (1) differential temporal dynamics of gray matter volume loss between cortical and subcortical regions, and (2) neuroplastic structural adaptations driven by football-specific visuospatial and cognitive demands.