Heterogeneity of schizophrenia: relationship to latency of neuroleptic response

Patients with an index diagnosis of schizophrenia were compared to patients with an index diagnosis of schizophreniform disorder to determine if they differed in latency to therapeutic response to haloperidol. The results of a survival analysis showed that patients with a diagnosis of schizophreniform disorder responded to haloperidol significantly more rapidly than did patients with a diagnosis of schizophrenia. Inspection of time-to-response slopes revealed that approximately 75% of the schizophreniform patients responded to neuroleptics on or before day 8 of treatment, whereas only 20% of the schizophrenic patients responded this rapidly. Forty percent of schizophrenic patients responded between day 8 and day 18, and 30% between day 18 and day 36. These results indicate that schizophreniform disorder has been successfully separated from schizophrenia in DSM-III, at least in relationship to drug response.