White Matter Hyperintensities and Microstructural Alterations in Contact Sport Athletes from Adolescence to Early Midlife.

Studies have demonstrated associations between cumulative concussion and repetitive head impact exposure (RHI) via contact sports with white matter (WM) alterations later in life. The course of WM changes associated with exposure earlier in the lifespan are unclear. This study investigated alterations in white matter (WM hyperintensity [WMH] volume and microstructural changes) associated with concussion and RHI exposure from adolescence to early midlife, as well as the interaction between exposure and age-cohort (i.e., adolescent/young adult compared to early midlife athlete cohorts) on WM outcomes. Participating football players included an adolescent/young adulthood cohort (n=82; Mage=18.41.7) and an early midlife cohort (37 former collegiate players approximately 15-years removed from sport; Mage=37.71.4). Years of football participation and number of prior concussions were exposures of interest. White matter outcomes included log-transformed manually segmented total WMH volume and neurite orientation dispersion and density imaging metrics of microstructure/organization (isotropic volume fraction[Viso], intra-cellular volume fraction[Vic], and orientation dispersion[OD]). Regression models were fit to test effects of concussion history, years of football participation, and age-cohort by years of football participation with WM outcomes. Spearman's correlations assessed associations between significant WM metrics and measures of cognitive and psychological function. A significant age-cohort by years of participation effect was observed for whole brain white matter OD, B=-0.002, SE=0.001, p=0.001. The interaction was driven by a negative association between years of participation and OD within the younger cohort, B=-0.001, SE=0.0004, p=0.008, whereas a positive association between participation and OD in the early midlife cohort, B=0.001, SE=0.0003, p=0.039, was observed. Follow-up ROI analyses showed significant interaction effects for OD in the body of the corpus callosum, genu of the corpus callosum, cingulum, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, posterior thalamic radiation (ps<0.05). Greater concussion history was significantly associated with greater Viso in the early midlife cohort, B=0.001, SE= 0.0002, p=0.010. Years of participation and concussion history were not associated with WMH volume, ps>0.05. Performance on a measure of executive function was significantly associated with years of participation, =.34, p=.04, and a trend was observed for OD, =.28, p=.09 in the early midlife cohort only. The global characterization of white matter changes associated with years of football participation were broadly similar and stable from adolescence through early midlife (i.e., microstructural alterations, but not macroscopic lesions). An inverse association between years of participation and orientation dispersion across age-cohorts may represent a process of initial recovery/reorganization proximal to sport, followed by later reduction of white matter coherence.

Urban Classification, Not COVID-19 Community Rates, Was Associated With Modes of Learning in US K-12 Schools?

OBJECTIVES: To identify factors associated with the decision to provide in-person, hybrid, and remote learning in kindergarten through 12th grade school districts during the 2020-2021 school year. METHODS: We performed a retrospective study evaluating school district mode of learning and community coronavirus 2019 (COVID-19) incidence and percentage positivity rates at 3 time points during the pandemic: (1) September 15, 2020 (the beginning of the school year, before Centers for Disease Control and Prevention guidance); (2) November 15, 2020 (midsemester after the release of Centers for Disease Control and Prevention guidance and an increase of COVID-19 cases); and (3) January 15, 2021 (start of the second semester and peak COVID-19 rates). Five states were included in the analysis: Michigan, Missouri, North Carolina, Ohio, and Wisconsin. The primary outcome was mode of learning in elementary, middle, and high schools during 3 time points. The measures included community COVID-19 incidence and percentage positivity rates, school and student demographics, and county size classification of school location. RESULTS: No relationship between mode of learning and community COVID-19 rates was observed. County urban classification of school location was associated with mode of learning with school districts in nonmetropolitan and small metropolitan counties more likely to be in-person. CONCLUSIONS: Community COVID-19 rates did not appear to influence the decision of when to provide in-person learning. Further understanding of factors driving the decisions to bring children back into the classroom are needed. Standardizing policies on how schools apply national guidance to local decision-making may decrease disparities in emergent crises.