Acute effects of haloperidol on cerebral cortex blood flow in normal and schizophrenic subjects

To evaluate the effects of neuroleptic medications on cerebral blood flow (CBF), cortical perfusion was quantified by the ¹³³xenon technique in 8 unmedicated schizophrenics and 9 healthy controls before, and 1 and 3 hours after, administration of haloperidol (5 mg per os). At 3 hours, the normal subjects, but not schizophrenic patients, showed a significant increase in global mean perfusion (17 ± 13%). Changes in CBF were not associated with plasma haloperidol levels or the presence of extrapyramidal side effects, and remained significant after controlling for pCO₂. The lack of change in CBF in schizophrenic patients following acute haloperidol administration may be due to prior neuroleptic exposure, absence of anxiety, or other nonspecific factors, or may reflect a more fundamental feature of underlying pathophysiology in schizophrenia.