Psychosocial treatments for people with co-occurring severe mental illnesses and substance use disorders (dual diagnosis): a review of empirical evidence.

Considerable research documents the health consequences of psychosis and co-occurring substance use disorders. Results of randomized controlled trials assessing the effectiveness of psychosocial interventions for persons with dual diagnoses are equivocal but encouraging. Many studies are hampered by small, heterogeneous samples, high attrition rates, short follow-up periods, and unclear description of treatment components. The treatments available for this group of patients (which can be tailored to individual needs) include motivational interviewing, cognitive-behavioral therapy, contingency management, relapse prevention, case management, and skills training. Regardless of whether services follow integrated or parallel models, they should be well coordinated, take a team approach, be multidisciplinary, have specialist-trained personnel (including 24-hour access), include a range of program types, and provide for long-term follow-up. Interventions for substance reduction may need to be further developed and adapted for people with serious mental illnesses. Further quality trials in this area will contribute to the growing body of data of effective interventions.