Inclusion Criteria:  Male or female; aged 18-70 years. Able to provide written informed consent. Meet DSM-5 diagnostic criteria for current moderate to severe alcohol use disorder (assessed via the MINI) Meet DSM-5 diagnostic criteria for current PTSD as assessed by the CAPS-5. Participants may also meet criteria for a mood disorder (except bipolar affective disorder, see Exclusion Criteria) or anxiety disorders. The inclusion of participants with affective and anxiety disorders is essential because of the marked frequency of the co-existence of mood and anxiety disorders among patients with AUD and PTSD. Concurrent substance use disorders (e.g., cannabis) are acceptable provided alcohol is the participant's primary substance of choice. Participants taking psychotropic medications will be required to be maintained on a stable dose for at least 4 weeks before study initiation.  Exclusion Criteria:  Meeting DSM-5 criteria for a history of or current psychotic or bipolar affective disorders, or with current suicidal or homicidal ideation and intent. Those participants will be referred clinically for services. Participants with current suicidal or homicidal ideation and intent. Participants on psychotropic medications which have been initiated during the past 4 weeks. Acute alcohol withdrawal as indicated by CIWA-Ar scores >8. Pregnancy or breastfeeding for people of childbearing potential. Currently enrolled in evidence based behavioral treatment for AUD or PTSD. Attendance at therapeutic activities (e.g., Alcoholics Anonymous) other than study sessions will be closely monitored using the Treatment Services Review. Participants with implanted electronic devices of any kind, including pacemakers, electronic infusion pumps, stimulators, defibrillators or similar.