Higher levels of physical activity (outdoor play & sport participation) were associated with greater white matter microstructure in children; no association was observed between screen time and white matter microstructure

Associations of physical activity and screen time with white matter microstructure in children from the general population. María Rodriguez-Ayllon et al. NeuroImage, October 9 2019, 116258. https://doi.org/10.1016/j.neuroimage.2019.116258

Highlights
•    Higher levels of physical activity were associated with greater white matter microstructure in children.
•    Outdoor play and sport participation were specifically related to white matter microstructure.
•    No association was observed between screen time and white matter microstructure.

Abstract: Physical activity and sedentary behaviors have been linked to a variety of general health benefits and problems. However, few studies have examined how physical activity during childhood is related to brain development, with the majority of work to date focusing on cardio-metabolic health. This study examines the association between physical activity and screen time with white matter microstructure in the general pediatric population. In a sample of 2,532 children (10.12 ± 0.58 years; 50.04% boys) from the Generation R Study, a population-based cohort in Rotterdam, the Netherlands, we assessed physical activity and screen time using parent-reported questionnaires. Magnetic resonance imaging of white matter microstructure was conducted using diffusion tensor imaging. Total physical activity was positively associated with global fractional anisotropy (β = 0.057, 95% CI = 0.016, 0.098, p = 0.007) and negatively associated with global mean diffusivity (β = −0.079, 95% CI = −0.120, −0.038, p < 0.001), two commonly derived scalar measures of white matter microstructure. Two components of total physical activity, outdoor play and sport participation, were positively associated with global fractional anisotropy (β = 0.041, 95% CI=(0.000, 0.083), p = 0.047; β = 0.053, 95% CI=(0.010, 0.096), p = 0.015 respectively) and inversely associated with global mean diffusivity (β = −0.074, 95% CI= (−0.114, −0.033), p < 0.001; β = −0.043, 95% CI=(-0.086, 0.000), p = 0.049 respectively). No associations were observed between screen time and white matter microstructure (p > 0.05). This study provides new evidence that physical activity is modestly associated with white matter microstructure in children. In contrast, complementing other recent evidence on cognition, screen time was not associated with white matter microstructure. Causal inferences from these modest associations must be interpreted cautiously in the absence of longitudinal data. However, these data still offer a promising avenue for future work to explore to what extent physical activity may promote healthy white matter development.