PROJECT SUMMARY / ABSTRACT The rise of social media in the lives of adolescent girls provides unprecedented opportunities to share personal details with others. While this behavior, known as intimate self-disclosure, can engender greater closeness and intimacy, it can also result in social rejection and invalidation, which are established risk factors for depression. This tradeoff is all the more heightened on social media given the potential for any risks associated with one's self-disclosure to be amplified to a scale that would not otherwise be experienced offline. The proposed project within this NRSA F31 application will leverage prospective longitudinal data from the NIH-funded Transitions in Adolescent Girls Study (N=174, baseline ages 10-13 years, 4 timepoints collected at 18-month intervals) and utilize an innovative and validated neuroimaging task that measures the intrinsic value of self-disclosure to characterize the neurobehavioral development of intimate (relative to superficial) self-disclosure and its association with depression in adolescent girls. This project will also examine whether neurobehavioral indices of intimate self-disclosure moderate the link between social media use and depression, especially in early adolescent girls. Adolescent girls are experiencing a growing mental health crisis, and there is a critical need to identify modifiable factors that are conferring increased risk for depression in this population. Intimate self- disclosure may be a malleable behavior, particularly on social media, that can be targeted through intervention to reduce the likelihood of experiencing depression in the context of high social media use. The overarching objective of the proposed project is to advance our knowledge of the development of intimate self-disclosure in adolescent girls and whether it represents a unique risk factor for depression in girls, especially in the context of high social media use. The goals of the proposed study are to test 1) how the decision to engage in intimate and superficial self-disclosure changes across typical adolescent development both at the neural and behavioral level, 2) whether an atypical developmental trajectory of intimate self-disclosure may confer risk for depression, and 3) which neurobehavioral indices of self-disclosure in conjunction with high social media use result in depression in adolescent girls. By identifying modifiable behaviors that confer risk for depression in the context of social media use, this project will inform future work on early prevention and intervention for depression in adolescent girls. This fellowship encompasses three critical training goals: 1) develop expertise in longitudinal modeling for the prediction of adolescent depression, 2) learn advanced methods for processing and analyzing longitudinal task-based fMRI data, and 3) professional development and impactful science communication to benefit youth and society. Completion of the research and training ...