PROJECT SUMMARY / ABSTRACT Alcohol use disorder (AUD) is highly heterogeneous in that its symptoms are highly varied and, often, non- overlapping across individuals. In theory, this phenotypic heterogeneity reflects the influence of multiple underlying causes, or etiologic mechanisms. This etiologic complexity makes AUD treatment very challenging; researchers have identified AUD’s etiologic complexity as the most critical barrier to progress in developing more effective, personalized treatments. Addiction theorists have identified a set of alcohol addiction research domain criteria (AARDoC) functional domains, believed to be important etiologic mechanisms for AUD. Yet, existing models meant to link these mechanisms to AUD-related behaviors and symptoms fail to consider etiology. Hence, many basic questions concerning the etiology of problematic drinking and AUD-related symptoms remain unresolved. The proposed work aims to identify the prospective contributions of functional domain neuro- behavioral indicators to the etiology of heavy drinking (HD) and AUD-related symptoms during adolescence and emerging adulthood, the decade of development when HD and AUD-related symptoms are most prevalent. We will enroll a target sample of 480 adolescents and emerging adults (160 in each of three partially overlapping age cohorts [50% female], pre-screened for elevated HD risk) to participate in a prospective study using an accelerated longitudinal design, which will allow us to characterize trajectories of alcohol involvement and AUD- related symptoms over a 10-year period of development within a five-year study. We will use a neuroclinical assessment approach to comprehensively characterize four functional domains—cognitive control/disinhibition (DIS), reward sensitivity (RS), anxiety (ANX), and incentive salience (IS)—using validated and reliable self- report, behavioral, and neurophysiological measures during each of three waves of data collection (15 months apart). Alcohol involvement, AUD-related symptoms, and social-environment factors will be assessed at 5-month intervals. Using this multi-wave, multimodal approach, we will address three specific aims: (1) characterize the influence of the functional domains on the etiology of alcohol involvement; (2) accounting for the influence of alcohol involvement, characterize the influence of the functional domains on the etiology of AUD-related symptoms; and (3) characterize the influence of HD on functional domain neurobehavioral indicators. Analyses will characterize how various combinations of domain indicators affect latent states of alcohol involvement (volume of consumption; patterns of use) and AUD-related symptoms (numbers of symptoms; clusters of symptoms) and transitions across latent states over time. This work will produce a unique and rich dataset, and its findings will directly inform the development of personalized intervention and treatment strategies that can be deployed to target the functionin...