Tracking Depression and Associated Modifiable Social-Emotional Factors in Adolescent Girls with Autism - PROJECT SUMMARY/ABSTRACT Adolescent girls with autism spectrum disorder (ASD) are at high risk for depression due to risk factors associated with female sex and ASD-related challenges. However, little empirical evidence is available on the psychosocial mechanisms of depression onset and change for girls with ASD, leaving no effective intervention to treat depression in this extremely vulnerable group. While social interaction and relationship challenges are particularly pronounced during adolescence, sufficiently nuanced longitudinal data is needed to understand how momentary and cumulative social and emotional experiences impact psychological well-being during this critical time in order to inform treatment development. The current proposal aims to investigate longitudinal trajectories and social mechanisms of depression in ASD during adolescence with a focus on girls. Three complementary studies are proposed to achieve the research objectives and provide necessary training to equip the candidate with advanced methodological and professional skills to transition into an independent research position. During the mentored K99 phase, two secondary data analyses will leverage existing data to generate initial evidence on depression and social experience in adolescent girls with ASD to: (1) Map trajectories of depression symptoms in girls with ASD and typical development (age 10 to 13) (Aim 1), using group-based longitudinal structural equation models (LSEM); (2) Profile daily social experiences relevant to negative mood and depressive symptoms in girls with ASD (Aim 2), using daily social experiences data collected with a cross-sectional sample of transition-age youths with ASD. To examine social-emotional protective and risk factors of depression (Aim 3), during the R00 phase, an accelerated longitudinal study with measurement bursts using ecological momentary sampling (EMA, study protocol piloted in K99) will be conducted to collect four waves of original data on 120 adolescent girls (60 ASD and 60 TD, age 14 to 16) over two years. Findings from the novel multi-method longitudinal study will directly inform development of targeted intervention by identifying how momentary social experiences, emotions, and coping strategies impact mood in the “moment” and in the long term, while considering the impact of individual- level characteristics. Through the carefully designed training activities and the institutional resources available at UCSF, the candidate will receive focused training on developmental psychopathology and pubertal development in ASD, hands-on clinical experiences in identifying and treating depression in girls with ASD, and methodological training in the state-of-art design and analyses of EMA during the K99 phase. With the strong support from a team of leading experts in their respective fields, the candidate will successfully establish her own line of research and become an independent researcher with unique expertise.