White matter integrity buffers the impact of screen time on inhibitory control in youth.

Excessive screen time is associated with reduced inhibitory control, a core component of executive function in children and adolescents. However, whether neurobiological factors buffer this effect remains unclear. The aim of this cross-sectional study was to investigate the relationship between screen time and inhibitory control and whether white matter integrity, a marker of axonal coherence, moderates this relationship in children and adolescents. A total of 150 participants aged 7-17 years completed the Stroop Color and Word Test, which was administered to assess inhibitory control. The participants underwent diffusion-weighted magnetic resonance imaging to enable evaluation of white matter integrity. Screen time was determined using caregiver reports. White matter integrity was indexed using fractional anisotropy (FA) in eight tracts: the bilateral superior longitudinal fasciculus (SLF) I/II, SLF III, arcuate fasciculus, and cingulum bundle. Whether white matter integrity moderates the relationship between screen time and inhibitory control was analyzed. Longer screen times were associated with weaker inhibitory control. FA in the right SLF I/II, SLF III, and arcuate fasciculus was inversely related to screen time. The right SLF I/II significantly moderated the relationship between screen time and inhibitory control. The effect of increasing screen time on reducing inhibitory control was observed only at lower FA levels. The moderating effect was not significant for any other tract. These findings indicate that white matter integrity may reflect neurocognitive resilience to screen time-related reductions in inhibitory control. The right SLF I/II FA may reflect individual differences in susceptibility to the cognitive correlates of screen exposure, highlighting the relevance of white matter integrity in understanding the variability in the neurocognitive outcomes associated with screen time.