Investigators will measure behavioral and brain responses following transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC) (anode on right DLPFC, cathode on the left DLPFC) delivered during cognitive control network (CCN) priming. In Phase I, the EEG provided validation of expected changes in these networks following tDCS stimulation of the DLPFC. In this current phase (II), the investigators will perform a larger randomized clinical trial (RCT) (active vs. sham control) to address long-term neurobehavioral outcomes, including opioid relapse, craving, and sustained EEG changes.

Investigators will perform an RCT in 100 opioid dependent participants who recently initiated buprenorphine or methadone. Participants will be randomized to receive five sessions of tDCS+CCN priming stimulation vs. sham tDCS+CCN priming. Participants will be assessed three times using electroencephalographic (EEG), once prior to tDCS+CCN priming, right after the completion of 5 sessions of tDCS+CCN priming (one week later), and again 10 weeks later.

This phase will address long-term (3- and 6-month) neurobehavioral outcomes, including opioid relapse, craving, and sustained EEG changes during a paradigm that challenges networks associated with craving (CR) and cognitive control (CCN). During the 24 weeks of buprenorphine or methadone maintenance treatment, the investigators will examine our primary clinical outcome, relapse (opioid use on >4 days per month and having an opioid positive urine screen), as well as days of opioid use.

Inclusion Criteria:

1. current opioid dependence
2. between 21-60 years of age
3. recent initiation of buprenorphine or methadone (≤90 days)
4. enrolled in Butler Hospital's Alcohol and Drug Inpatient Unit, Alcohol and Drug Partial Hospital Treatment Program, Intensive Outpatient Services, or Outpatient Services at Butler Hospital OR receive opioid-treatment services in the community.

Exclusion Criteria:

1. current diagnosis of organic brain disorder (e.g., Parkinson's disease, Huntington's disease, multiple sclerosis, intracranial mass/infection, hydrocephalus)
2. bipolar, schizophrenia, schizoaffective, or schizophreniform disorder, or current psychosis associated with any disorder
3. current suicidality
4. evidence of significant neurocognitive dysfunction
5. conditions associated with heightened tDCS risks, e.g., seizure disorder, nonremovable intracranial metal objects (other than dental fillings and dental implants), skin disease or active lesions on the scalp, migraine/other headache disorder with significant active symptoms, traumatic brain injury or skull fracture within the past year, any implanted medical devices or device components that can interact with electromagnetic fields or are controlled by physiological signals
6. probation/parole requirements or an upcoming move that might interfere with protocol participation
7. planning to terminate buprenorphine or methadone in less than 3 months
8. current pregnancy or plan to become pregnant in the next month.

Data will be shared online at ICPSR.

1-year after the end of the study