Cerebral glucose metabolic rates were determined in normal control
subjects (n = 26) and schizophrenic patients with tardive dyskinesia (n =
14). Globus pallidus and primary motor cortex (precentral gyrus) metabolic
values divided by those of the cerebral hemispheres were significantly
increased in the patient group. A similar metabolic pattern has not been
reported for schizophrenic patients without tardive dyskinesia, and the
abnormalities were demonstrated despite the normal appearance of the basal
ganglia on X-ray CT. The findings differed markedly from the reduced
metabolic rates of the basal ganglia previously identified in other
choreiform disorders, including Huntington's and Wilson's diseases. The
findings suggest that tardive dyskinesia is characterized by increased
pallidal synaptic activity resulting from either altered striatopallidal
input or increased pallidal interneuron firing.Abstract Teaser