Project Summary/Abstract Etiology, maintenance, and recovery from alcohol use disorder (AUD) are each highly heterogeneous processes, and variability in the clinical course of AUD poses challenges for the development of effective treatments. Recently proposed models of AUD heterogeneity are informed by neurobiological mechanisms underlying the development and maintenance of alcohol use. For example, the Alcohol and Addictions Research Domain Criteria (AARDoC) and the Addictions Neuroclinical Assessment (ANA) have been used to explain neurobiological, behavioral, and genetic heterogeneity in AUD. Another phenotype for classifying variability within AUD is reward and relief drinking, or the extent to which individuals seek alcohol to enhance positive experiences and social interaction (reward drinking) versus the extent to which individuals seek alcohol to relieve negative emotional and somatic states (relief drinking). Processes underlying reward/relief drinking correspond to the cycle of addiction and this phenotype is complementary to AARDoC/ANA domains. Previous findings indicate the utility of reward/relief drinking phenotypes in matching patients to AUD pharmacotherapies, with high reward drinkers responding better to naltrexone versus placebo. Despite promising findings for precision medicine, limitations of current measures of reward/relief drinking may stymie efforts to translate findings to clinical practice. Different measures of reward/relief drinking have been used across studies, the construct validity of these measures has not been thoroughly assessed, and scoring guidelines to identify reward/relief drinkers do not exist. To address these methodological issues and gaps in the literature, the primary goal of the proposed project is to validate a brief measure of reward/relief drinking that can be easily administered and scored in clinical practice. Specifically, we aim to refine and validate a brief version of the Inventory of Drinking Situations (IDS), which has been utilized to identify reward/relief subgroups in two prior studies of the reward drinker-naltrexone response hypothesis. First (Aim 1), we will conduct secondary data analysis of three large studies of individuals in AUD treatment (N=1,152), with varying levels of AUD severity, to identify a brief version of the IDS and a scoring algorithm for this measure. Two of these studies were clinical trials of AUD pharmacotherapies, and we will assess the clinical utility of this brief measure by examining response to naltrexone. Second (Aim 2), we plan to collect data from individuals with hazardous and harmful alcohol use (N=65) to examine relationships among the brief IDS and a range of related constructs assessed with self-report assessments and interviews, reactivity to alcohol and negative images, and reward/relief drinking processes in near real time using ecological momentary assessment (EMA). Thus, we plan to use advanced analytic methods and a multimethod approach to id...