Responses to apomorphine, amphetamine, and neuroleptics in schizophrenic subjects.

Twenty-one schizophrenic subjects, who had been neuroleptic-free, were tested for responsiveness to dopaminergic agonists: Apomorphine emesis threshold was determined and change in psychopathology after 0.5 mg/kg d-amphetamine orally was rated. The subjects' subsequent response to neuroleptic treatment were also determined. Sensitivity to apomorphine emesis was also determined in a nonschizophrenic control group. Apomorphine emesis threshold was not significantly different in the schizophrenic and control groups. Correlations were done between baseline psychopathology, apomorphine sensitivity, and changes in psychopathology after amphetamine and after neuroleptic treatment. On the Brief Psychiatric Rating Scale (BPRS), baseline psychopathology correlated with improvement after neuroleptics and, on the clinical global impressions (CGI), increase of psychopathology after amphetamine also correlated with improvement after neuroleptic treatment. An inverse correlation was found between several indices of sensitivity to amphetamine (psychopathology change) and emetic sensitivity to apomorphine. An examination of individual subjects' responses to amphetamine and, subsequently, neuroleptics, suggested that in the absence of significant clinical change after amphetamine a brisk therapeutic response to neuroleptics was rare.