Objective: Although the clinical reality of substance dependence and/or abuse among schizophrenia patients is widely acknowledged, the interaction of these diagnoses is not well understood. Perhaps the largest study documenting the comorbidity of substance abuse is the Epidemiologic Catchment Area (ECA) study, which found the rate to be 47% in schizophrenia patients (1). The present study examined substance use and compared the broad categories of substance users versus nonusers vis-à-vis schizophrenic symptomatology, hospitalizations, compliance, and demographic variables. We further examined the two subcategories of alcohol versus other substances of abuse (hereafter called "drugs") to determine differences.
Methods: Data were collected by the same person retrospectively from the charts of schizophrenia outpatients in a public inner city mental health center. Patients must have had at least 10 outpatient visits within a 2-year period for data to be used.
Results: Data were compiled from 262 charts. Of the schizophrenia patients, 55% had a history of past or current substance use. Consistent with previous reports, substance-using schizophrenia patients were more likely to be younger and male than nonusers. Substance users had significantly more hospitalizations and more outpatient visits with positive symptoms. There was also a higher rate of missed appointments in the substance-using patients, and there was a correlation between missed appointments and hospitalizations. As for the differences in the two subcategories of alcohol versus drugs, drug users had notably more negative symptoms, except in those cases for which the alcohol user required treatment for alcoholism. Current drug use also correlated with higher tardive dyskinesia scores, higher incidence of cognitive deficiency, less education, and higher average neuroleptic dose than with nonuse or alcohol use.
Conclusion: These results extend the previous findings to a large inner city group of subjects and to a population that is at high risk for relapse. Our findings further emphasize the impact of substance use on outcome in schizophrenia and the need for more research on the nature and treatment of the patient with a dual diagnosis.