EFFECTS OF SUBSTANCE-ABUSE ON HALLUCINATION RATES AND TREATMENT RESPONSES IN CHRONIC PSYCHIATRIC-PATIENTS

Background: Few data systematically document the effects of illicit dr ug exposure on psychotic illness. We examined the effect of substance abuse on rates and treatment responses of hallucinations in a chronic psychiatric population. Method: 113 cooperative patients consecutively admitted to a state psychiatric hospital were administered the Struct ured Clinical Diagnostic Interview for DSM-III-R, a Hallucination Inte rview, and an inventory of past and current substances of abuse. Demog raphic information was obtained on 104 of 108 patients who declined in terview. Medication dosage was analyzed for one third of the interview ed sample; hospital records, nursing reports, contacts with relatives, and urine drug screens were used to confirm information from patient interviews. Hallucination rates and response were compared by diagnosi tic groups (chi-square). Results: Noninterviewed patients had more fre quent hospitalizations, more patients diagnosed with psychosis not oth erwise specified or schizoaffective disorder, and fewer females with c omorbid substance abuse than the study population. Among interviewed s ubjects, those with substance abuse and psychiatric illness had first admissions at an earlier age than patients with no substance abuse (p = .005). Schizophrenics experienced higher rates of visual (p = .04) a nd olfactory (p = .05) hallucinations when using illicit drugs. Substa nce abuse was associated with decreased treatment responsiveness of au ditory (p < .03) and tactile (p < .004) hallucinations in schizophreni c or manic patients. Compared with nonparanoid patients, there was a t rend for paranoid schizophrenics with substance abuse to experience mo re frequent visual (p = .09) and tactile (p = .06) and more refractory auditory (p = .08) hallucinations. No differences in medication dosag es were found between patients with treatment-responsive and treatment -refractory hallucinations. Conclusion: Abused substances may interact selectively with primary psychiatric illness to increase rates and tr eatment resistance of specific hallucination modalities; etiologies ar e discussed.