The goal of this K23 award is to develop the applicant into an independent investigator with advanced multimodal neuroimaging and clinical research methods skills to support his career objective of establishing a line of research investigating reward brain circuitry as a shared etiological vulnerability to substance use disorder and major mood disorder co-occurrence. With this award, the applicant will investigate the structure and function of reward brain circuitry in co-occurring alcohol use disorder (AUD) and bipolar disorder (AUD+BD) which remains largely unknown to support the development of more precise neurobiological targets for the treatment of AUD+BD. The proposed career development and training plan is directly aligned with his prior experience in child/family clinical psychology, social reward and decision-making, utilization of high-risk designs, and ongoing adult AUD(+/-BD) neuroimaging research. With the support of this renowned mentorship team, the applicant will: 1) gain advanced knowledge and proficiency in functional magnetic resonance imaging (fMRI), diffusion kurtosis imaging (DKI), and sophisticated analyses with these data; 2) develop a deep understanding of the neurobiology of AUD and BD from adolescence into adulthood; 3) become highly adept at conducting family-related alcohol and BD clinical research; and 4) improve his grantsmanship for a smooth transition to research independence. These goals will be achieved through rigorous hands-on training in fMRI and DKI; the successful completion of neuroimaging statistics coursework with expert consultation support; guided reading series on AUD and BD neurobiology, assessment, and treatment; intensive mentorship in conducting neuroimaging research with families; and the successful completion of various on-campus grantsmanship trainings. The objective of the proposed multimodal neuroimaging study is to define reward brain circuitry structure and function among sets of parents with AUD+BD and their unaffected adolescent offspring (dyads) against dyads defined by parental AUD alone (n=25 per group). This study is directly aligned with two foremost NIAAA initiatives through focus on increasing understanding of AUD neurobiology in the context of co-occurring psychopathology across age groups. The proposed aims will measure reward circuitry brain function using social reward and decision-making fMRI tasks paired with DKI for measurement of white matter (WM) pathway microstructure. The central hypotheses are: 1) sets of adults and their unaffected offspring (dyads) with AUD+BD relative to AUD alone will exhibit hyperactivation to reward (with perturbed functional connectivity) due to BD co-occurrence, and 2) WM microstructural integrity will be reduced in sets of AUD+BD dyads relative to AUD dyads. The results of this K23 study will generate important preliminary data for a longitudinal R01 establishing reward-related endophenotypes for AUD+BD patients who are currently underserved by...