POSITRON-EMISSION TOMOGRAPHY IN TARDIVE-DYSKINESIA

Cerebral glucose metabolic rates were determined in normal control sub jects (n = 26) and schizophrenic patients with tardive dyskinesia (n = 14). Globus pallidus and primary motor cortex (precentral gyrus) meta bolic values divided by those of the cerebral hemispheres were signifi cantly increased in the patient group. A similar metabolic pattern has not been reported for schizophrenic patients without tardive dyskines ia, and the abnormalities were demonstrated despite the normal appeara nce of the basal ganglia on X-ray CT. The findings differed markedly f rom the reduced metabolic rates of the basal ganglia previously identi fied in other choreiform disorders, including Huntington's and Wilson' s diseases. The findings suggest that tardive dyskinesia is characteri zed by increased pallidal synaptic activity resulting from either alte red striatopallidal input or increased pallidal interneuron firing.