Despite conscious intentions to remain abstinent, persons with substance use disorders often find that negative emotions and environmental cues automatically "trigger" drinking and other substance use. This study aims to test whether activating the baroreflex mechanism can be used "in the moment" to help resist drinking triggers. It consists of 3 phases (Recruitment, Intervention, Follow-up).

Stage 1: Trained research staff conduct a comprehensive clinical interview and questionnaires to assess participant's mood, substance use, and triggers. Participants are paired with a Primary Research Clinician (PRC) who will work with them during the intervention.

Stage 2: Approximately 4 weeks after intake into the Center for Great Expectations Intensive Outpatient program, an 8-week intervention begins. Pre-and post-intervention laboratory sessions occur at Cardiac Neuroscience Laboratory, Center of Alcohol Studies, Piscataway, NJ. Some participants take part in pre- and post-intervention neuroimaging sessions (Rutgers University Brain Imaging Center, Newark, NJ). Participants are randomized into an active intervention or control group after the pre-intervention lab session. They are given an iPhone and trained to use a paced breathing app that is pre-loaded onto the phone. Participants in both groups use their app any time they anticipate or experience a trigger to drink or use drugs. Participants are compensated for their use of the app and the time for participation. To ensure that participants are correctly performing the paced breathing task, their PRC visit with them weekly to provide coaching sessions using a computer-based biofeedback program. During the 4th week, ECG and respiration data are collected. Participants also complete questionnaires about mood and triggers, and provide feedback on the usefulness of the app.

During the lab sessions, participants complete a series of questionnaires and ECG, blood pressure and respiration are collected during four 5-minute tasks (resting baseline, non-resonance breathing, resonance breathing, and visual processing/attention). During the neuroimaging sessions, participants are placed in the scanner for structural scans and four 5-minute tasks (as tasks as previously noted); ECG and blood pressure are recorded.

Stage 3: Participants are re-contacted 1 and 3 months after the intervention to complete questionnaires about their quality of life across multiple domains and the usefulness of the app.

Inclusion Criteria:

• Women over age 18
• Women diagnosed with substance use disorder
• Women participating in IOP at Center for Great Expectations, New Brunswick, NJ

Exclusion Criteria:

• Pregnancy

Adverse event data were collected from screening until the end of follow-up, up to 6 months after enrollment.

The effect of the intervention could not be determined due to the influences of the opioid epidemic that severally restricted recruitment of participants with primary alcohol use disorders and the nationwide shutdowns that occurred due to the COVID-19 pandemic. The final sample was statistically underpowered ; thus, analyses focused on the uptake of the intervention by individuals in outpatient treatment for opioid and other use disorders.