• Dual diagnosis;
  • motivational interviewing;
  • psychosis


Aims  This pilot study examined the efficacy of a two-session motivational interview adapted for dually diagnosed psychotic and drug-related disordered patients (DDMI) in comparison to a two-session standard psychiatric interview (SI).

Design  The study used a randomized controlled trial design. Participants received either DDMI or SI and were assessed at baseline, 4-, 8- and 12-week follow-up points. The principal analysis for examination of treatment effects across time was a random effects regression model.

Setting  Both DDMI and SI interviews served as pre-admission intake interventions to an ambulatory specialty dual diagnosis intensive out-patient and partial hospital program.

Participants  Forty-four treatment-seeking participants (DDMI = 24; SI = 20) who had co-occurring psychotic and drug-related disorders were assigned randomly to the treatment conditions.

Measurements  Primary outcomes were days of primary drug use, secondary drug use, alcohol use and psychotropic medication adherence, proportion of participants admitted into the program and days of attendance.

Findings and conclusions  DDMI and SI resulted in improved treatment outcomes, but there were no main effects for the sample as a whole. Separate examination of primary cocaine and primary marijuana using subsamples, however, suggested that DDMI resulted in significantly better primary drug treatment outcomes for the cocaine-using group, whereas SI resulted in significantly better primary drug treatment outcomes for the marijuana-using group. These findings indicate that MI may not work equally well for all types of psychotic disordered dually diagnosed patients and that alternative approaches may be as effective in fostering improved substance use treatment outcomes for subgroups of these individuals.