Substance abuse is the most common comorbid complication of severe mental illness. Current clinical research converges on several emerging principles of treatment that address the scope, pace, intensity, and structure of dual-diagnosis programs. They include a) assertive outreach to facilitate engagement and participation in substance abuse treatment, b) close monitoring to provide structure and social reinforcement, c) integrating substance abuse and mental health interventions in the same program, d) comprehensive, broad-based services to address other problems of adjustment, e) safe and protective living environments, f) flexibility of clinicians and programs, g) stage-wise treatment to ensure the appropriate timing of interventions, h) a longitudinal perspective that is congruent with the chronicity of dual disorders, and i) optimism.

Utilization and cost of institutional and outpatient services were prospectively measured over 1 year for three groups of schizophrenic patients: current substance abusers, past substance abusers, and those without a history of substance abuse. Current abusers had significantly greater utilization and cost of institutional (hospital and jail) services. Current abusers also had greater utilization of emergency services. There were no significant differences between the groups in utilization and cost of other services, including psychosocial rehabilitation, outpatient treatment (case management, psychotherapy, and psychiatric visits), and housing supports. The implications for developing cost-effective treatments for dually diagnosed individuals are discussed.