Longitudinal associations between screen time activities and working memory neural signatures in adolescents: Sex differences and contextual moderation.

INTRODUCTION

Adolescent screen media activity (SMA) has increased, yet its longitudinal associations with neurocognitive development and mental health remain unclear across activities and contexts.

METHODS

This longitudinal cohort study used data from the Adolescent Brain Cognitive Development (ABCD) Study (release 6.0) with four assessments (baseline, year 2, year 4, and year 6). Participants were recruited across 21 U.S. sites to reflect demographic diversity. Children with valid neuroimaging and behavioral data were included, adjusting for demographic, behavioral, and psychiatric confounders. Working memory (WM) neural signature (NS) scores were derived using elastic net classification of EN-back fMRI activation during 0-back and 2-back conditions. SMA included time spent video gaming, watching television, texting, and social media. Cognitive performance was measured using EN-back accuracy, and mental health symptoms using Child Behavior Checklist internalizing and externalizing scores. Moderation analyses examined family conflict, sleep disturbance, and physical activity.

RESULTS

The analytic sample included 9931 participants (47.2% female). Higher NS scores were associated with better 0-back and 2-back accuracy. Greater video gaming, texting, and television watching were associated with lower NS scores. Sex-stratified analyses showed among males, more screen time was associated with lower NS scores, a multivariate measure of how separable neural activation patterns are between the 2-back and 0-back conditions. These associations were specific to the EN-back task and were adjusted for general cognitive ability. Higher degrees of family conflict increased the association between NS with texting, and video gaming and externalizing symptoms among males. Sleep disturbance and physical activity also moderated associations with internalizing and externalizing symptoms, with sex-specific patterns.

CONCLUSIONS

WM-related neural function was associated with cognitive performance and SMA engagement, differing by sex and environmental context, highlighting complex associations between neurocognitive development, media use, and mental health.