Developmental changes in brain function linked with addiction-like social media use two years later.

Addiction-like social media use (ASMU) is widely reported among adolescents and is associated with depression and other negative health outcomes. We aimed to identify developmental trajectories of neural social feedback processing that are linked to higher levels of ASMU in later adolescence. Within a longitudinal design, 103 adolescents completed a social incentive delay task during 1-3 fMRI scans (6-9th grade), and a 4th self-report assessment of ASMU and depressive symptoms ∼2 years later (10-11th grade). We assessed ASMU effects on brain responsivity to positive social feedback across puberty and relationships between brain responsivity development, ASMU symptoms, and depressive symptoms while considering gender effects. Findings demonstrate decreasing responsivity, across puberty, in the ventral media prefrontal cortex, medial prefrontal cortex, posterior cingulate cortex, and right inferior frontal gyrus associated with higher ASMU symptoms over 2 years later. Significant moderated mediation models suggest that these pubertal decreases in brain responsivity are associated with increased ASMU symptoms which, among adolescent girls (but not boys), is in turn associated with increased depressive symptoms. Results suggest initial hyperresponsivity to positive social feedback, before puberty onset, and decreases in this response across development, may be risk factors for ASMU in later adolescence.