Impact of Personality Disorder on the Treatment of Psychiatric Disorders in People Receiving Methadone-Assisted Treatment.

This study evaluates personality disorder as a moderator of psychiatric treatment response in people receiving methadone-assisted treatment. Participants (N = 125) were enrolled in a 12-week parent study that evaluated the impact of incentives on attendance to psychiatric care. All participants had a current DSM IV-R Axis I disorder and were classified based on presence of an Axis II disorder: Axis I-only (n = 46) versus Axis I + II (n = 79). All participants received an identical protocol of psychiatric and substance use disorder care. Although Axis I + II participants endorsed more psychiatric distress (on the Hopkins Symptom Checklist-Revised) throughout treatment, they reported significant reductions in distress that paralleled reductions reported by Axis I-only participants. Rates of substance use were low and similar across groups. Results support the benefits of integrated psychiatric and substance use care for people with opioid use disorder, with or without a co-occurring personality disorder.