Combined tDCS and Cognitive Training as an Adjunctive Treatment in Opioid Use Disorder

Inclusion Criteria:

* Ability to provide consent and comply with study procedures
* Diagnostic and Statistical Manual of Mental Disorders criteria for OUD
* Undergoing medication treatment for OUD. Participants may have current comorbid drug use, but primary diagnosis must be OUD
* Intention to remain in the study until intervention completion.

Exclusion Criteria:

* Any medical condition with neurological sequelae
* Head injury resulting in skull fracture or loss of consciousness of \>30 minutes
* Any tDCS or MRI contraindication (tDCS: history of seizures, metallic cranial plates/screws or implanted device, history of eczema on scalp. MRI: unapproved metallic implants, pacemakers or any other implanted electrical device, shrapnel, metallic braces, non-removable body piercings, pregnancy, breathing or movement disorder, or claustrophobia)
* Any psychotic disorder (participants with other treated and stable psychiatric disorders will be included)
* Presence of a condition that would render study measures impossible to administer or interpret
* Age younger than 18
* Primary current substance use disorder on a substance other than opioids except for caffeine or nicotine
* In treatment instead of jail
* Pregnancy
* Disrespectful behavior towards the investigators and staff.