EFFECTS OF REPETITIVE NON-CONCUSSIVE HEAD IMPACT EXPOSURE ON DEFAULT MODE NETWORK CONNECTIVITY AMONG YOUTH FOOTBALL PLAYERS

Abstract

Sports-related concussions have been shown to alter default mode connectivity in the brain. However, less is known about repetitive non-concussive head impact exposure, especially among understudied youth athletes. The purpose of this investigation was to determine if repetitive sports-related head impact exposure alters default mode network (DMN) connectivity among youth football players compared to a non-contact sport control group. Also, we investigated a dose response relationship to impact exposure using a multiple comparison test including control, high and low head impact exposure football player groups. Seventy-three male youth football players and 25 age-matched male non-contact sports controls were recruited for this study. None of them had a history of concussion before or during the sports season. Participants received pre- and post-season MRI including resting-state BOLD fMRI. Pre-processed fMRI data were co-registered to structural T1-weighted images. A DMN seed was created from the orthogonal slices of the spatial cross-correlation from the independent component analysis (ICA) spatial maps and used to extract individual DMNs for pre- and post-season data. A delta metric was computed by subtracting pre- and post-season DMN data to estimate connectivity strength changes. Two statistical analyses, the voxel-wise 2 sample t-test and a multiple comparison test, were conducted to examine between group differences.