Neurocognitive Mechanisms Underlying Smartphone-Assisted Prevention of Relapse in Opioid Use Disorder

This study investigates how a smartphone app can support people in medication-assisted treatment (MAT) for opioid use disorder and help prevent relapse. It also includes an optional brain imaging (MRI) component to understand the brain mechanisms involved. You may be eligible if: - You are 18 years old or older - You are in Phase I of medication-assisted treatment for opioid use disorder (receiving weekly clinic visits with limited take-home doses) - You are willing to use a smartphone if assigned to the app intervention group You may NOT be eligible (for the MRI sub-study) if: - You have a history of neurological, cardiovascular, or infectious disease - You have had a loss of consciousness of 20 or more minutes or brain trauma - You are pregnant - You have MRI contraindications (metal implants, claustrophobia, etc.) Talk to your doctor to see if this trial is right for you.