OBJECTIVE: The purpose of this study was to find predictive criteria for
response to clozapine. METHOD: Single photon emission computed tomography
studies of cerebral perfusion were done in 24 treatment- resistant
schizophrenic patients while they were taking typical neuroleptics and
again after they had been treated with clozapine for 6 months. Perfusion
ratios of the subjects categorized as responders or nonresponders to
clozapine and of the subjects in the two treatment conditions were
compared. The ratios with significant between-group differences were
compared to those from a normal database. RESULTS: Before clozapine, while
taking neuroleptics, subjects who became responders to clozapine showed
higher thalamic, left basal ganglia, and right prefrontal perfusion.
Nonresponders to clozapine had lower prefrontal perfusion and responders
had higher subcortical perfusion than subjects in the normal database. The
subcortical perfusion of the responders decreased when they received
clozapine. CONCLUSIONS: The study of cerebral perfusion may contribute to
the prediction of response to clozapine.