We conducted a double-blind placebo controlled study of the effects of .005 mg/kg of apomorphine, a direct acting dopamine agonist, on regional cerebral blood flow (Xe-133 rCBF) during a prefrontal cortex activation procedure in six drug-free schizophrenic patients. Following a simple Numbers Matching control task, each subject received either placebo or active apomorphine (SQ) and then performed a prefrontal activation task (Wisconsin Card Sort). In each patient with schizophrenia, apomorphine increased relative prefrontal flow (paired t =2.93, n=6, p=.03) during the prefrontal cortex activation procedure. In addition, during the prefrontal activation task patients showed greater increases in relative prefrontal flow compared to the control task with apomorphine than with placebo (paired t=3.31, n=6, p=.02). The results suggest that in schizophrenia enhanced prefrontal dopamine increases relative rCBF in the prefrontal cortex, an area implicated by recent cognitive and physiological studies in the pathophysiology of schizophrenia.
