No D2 Receptor Increase in PET Study of Schizophrenia

To the Editor.— Densities of D₂dopamine receptors in postmortem brain tissue from schizophrenic patients have been found to be higher than those in control brains.¹,²The pathophysiologic significance of this finding has been questioned, since elevated receptor densities may be caused by neuroleptic treatment.³It is now possible to examine D₂dopamine receptor binding in the brains of living human subjects by means of new brain-imaging techniques and radiolabeled receptor ligands. Using a gamma camera and⁷⁷Br-Bromospiperone, Crawley et al⁴reported evidence of a slight increase in D₂dopamine receptors in a group of schizophrenic patients. Using positron emission tomography (PET) and¹¹CN-Methylspiperone, Wong et al⁵recently reported a twofold to threefold elevation of D₂dopamine receptor densities in the major basal ganglia of ten drug-naive and five previously treated schizophrenic patients. We previously used PET and