Social Media Use and Early Adolescent Brain Structure: Findings from the Adolescent Brain Cognitive Development (ABCD) Study

• We analyzed associations of social media use and sMRI measures in 7,614 adolescents. • Early social media use was linked to widespread lower cortical thickness. • Regions identified were in default mode, executive, and visual processing networks. • Social media addiction showed no cortical structural changes in ROI analysis. Many adolescents initiate social media use during early adolescence, but the associations of early social media use with neurodevelopment have not been extensively studied. We utilized neuroimaging data from the U.S. Adolescent Brain and Cognitive Development (ABCD) Study to investigate the association of social media usage (hours per day) or social media addiction (Social Media Addiction Questionnaire) with brain morphology in early adolescence. We analyzed data from 7,614 participants with high-quality structural MRI and complete covariate data at Year 2 (2018–2020, ages 10–13). In addition to pre-defined cortical regions, we performed vertexwise analysis using Fast and Efficient Mixed Effects Algorithm (FEMA), which is unbiased by arbitrary borders between atlas-based brain regions and provides higher spatial resolution. After adjusting for demographics, socioeconomic factors, genetic ancestry, and scanner features, higher average daily social media use was significantly associated with lower total cortical thickness and volume. Region-of-interest (ROI) and vertexwise analysis identified broad regions with lower cortical thickness across the prefrontal cortices, temporal lobe, occipital lobe, and parietal lobe associated with both social media use and social media addiction, which overlap with key nodes of the default mode network, prefrontal executive control networks, and visual processing and attention networks. Social media addiction was not significantly associated with differences in brain morphology in ROI analysis. Our findings in a large nationwide population demonstrate that higher social media usage is associated with variation in cortical morphology, but future studies are required to establish the directionality of this association.