Psychopathology in dual-diagnosis and nonaddicted schizophrenics: are there differences?

Analysis of 447 schizophrenic inpatients found a lifetime prevalence for substance use of 42.9% (3-month prevalence 29%). While the overall differences were small between schizophrenics using (dual diagnosis) and those not using substances, dual-diagnosis patients in general reported more positive symptoms, especially more intense hallucinations. These differences were observed in patients with current (3-month) substance use on admission but not on discharge, possibly as a result of substance use. The most marked differencses were in previous suicide attempts and delinquency, which were more prevalent in dual-diagnosis schizophrenics. These findings indicate that patients with dual diagnosis are more disturbed than other schizophrenics. We discuss the implications for the self-medication hypothesis for substance use in schizophrenia and future research in this area are discussed.