NAC for Treating Comorbid PTSD and SUD

Inclusion Criteria: * Male or female, any race or ethnicity, age 18 to 75 years old. * U.S. military Veteran, including National Guard and Reservists. * Able to comprehend English. * Meet Diagnostic and Statistical Manual (DSM-5) criteria for current alcohol use disorder (AUD) and/or substance use disorder (SUD). * Meet DSM-5 criteria for current PTSD or subthreshold PTSD. Subjects may also meet criteria for a mood disorder (except bipolar affective disorder, see Exclusion Criteria) or other anxiety disorders (e.g., panic disorder, agoraphobia, social phobia, generalized anxiety disorder). The inclusion of subjects with affective and other anxiety disorders is essential because of the marked frequency of the co-existence of mood and other anxiety disorders among patients with PTSD (Brady et al., 2000; Kessler et al., 2005). * Subjects taking psychotropic medications will be required to be maintained on a stable dose for at least four weeks before treatment initiation. This is because initiation or change of medications during the course of the trial may interfere with interpretation of results. * Must consent to random assignment to N-acetylcysteine (NAC) or placebo. * Must consent to complete all treatment and follow-up visits. Exclusion Criteria: * Subjects meeting DSM-5 criteria for a history of or current psychotic or bipolar affective disorders, as the study protocol may be therapeutically insufficient. * Subjects with a current eating disorder (bulimia, anorexia nerv…