PROJECT SUMMARY In the midst of the opioid epidemic, methamphetamine use is emerging as the next substance use crisis with disproportionately increasing prevalence in men who have sex with men (MSM), high relapse rates and no FDA-approved treatments for individuals with methamphetamine use disorder (MUD). One of the major contributors to relapse is the enhanced motivated arousal (cue-reactivity) to drug-related cues, even after protracted abstinence that leads to an increase in craving and drug-seeking. Although cue-reactivity is studied widely in other substance use disorders, its study is scarce in MUD and non-existent in MSM with MUD, creating a critical gap in knowledge needed for unbiased assessment of disease severity and treatment outcomes in this rapidly growing clinical population. Therefore, in this bi-phased study, we propose to first identify a psychophysiological marker of methamphetamine cue-reactivity and its incubation with abstinence from methamphetamine use and examine group-differences between MSM and non-MSM MUD. Subsequently, in the second phase we propose to longitudinally assess incubation of cue-reactivity, its reduction with cognitive reappraisal (CR; a self-regulation technique) and examine the impact of CR on clinical outcomes in MSM with MUD. In light of preliminary findings from our group, we hypothesize that LPP, an electroencephalography-derived marker of drug cue-reactivity, will track the incubation of methamphetamine cue-reactivity and its CR-mediated reduction, which in turn will be associated with improved clinical outcomes in MSM with MUD. In the R61 phase, we will cross-sectionally compare the LPP-assessed cue-reactivity between currently using (Group 1) and abstinent (1-3 months; Group 2) individuals with MUD (50% MSM in each group, matched on HIV status), and examine in-task changes in cue-reactivity with CR technique. In the R33 phase, we will assign a cohort of MUD to either the CR+ (Cognitive Reappraisal training) or the CR- (no Cognitive Reappraisal training) group (all MSM, matched on HIV status), and cue-reactivity will be assessed longitudinally at <2 weeks, 2 months, to 3 months after abstinence initiation. Successful completion of these aims will identify an EEG-based, objective, and clinically useful marker of methamphetamine cue-reactivity, and will delineate the impact of CR on methamphetamine cue-reactivity in relation to treatment response in MSM with MUD. This work will be the beginning of mechanistic research into the role of incubation of methamphetamine cue-reactivity and its reduction as a reliable and clinically meaningful outcome measure, establishing an empirical foundation to develop an intervention for MUD and possibly in other addictions.