The Associations Between Football Exposure, Concussion History and Playing Position on Cerebral White Matter Integrity and Neurocognitive Performance

Diffusion tensor imaging (DTI) has emerged as an important tool for quantitative analysis of white matter (WM) integrity following sport-related concussions. The purpose of this research was to investigate the variances in WM integrity (defined by fractional anisotropy (FA) and medial diffusivity (MD)) and neurocognitive performances in retired college and professional football athletes based on concussion history, duration of playing career, and playing position. MRI scans and neurocognitive test scores from 32 former college and 31 former age-matched professional players (avg age=58.5 SD=3.7) were compared. A permuted, voxel-wise 3x2 ANOVA was performed on the WM skeleton to investigate the main and interaction effects on WM integrity. Threshold-free cluster enhancement (TFCE) was used to identify clusters of significantly different FA or MD and post-hoc univariate analyses were used to determine the direction of interaction effects. A priori alpha level was set at 0.05 after correction for multiple comparisons. Differences in FA were observed in 3 clusters in the forceps minor and genu of the corpus callosum for the concussion by position interaction. Post-hoc analysis of the peak voxels within each cluster revealed consistently lower FA in non-speed athletes with 3+ concussions as compared to those with 01 concussions (Cohen’s d: 0.89, 0.95, and 1.29; P