A SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY SCAN STUDY OF STRIATAL DOPAMINE D-2 RECEPTOR-BINDING WITH I-123 EPIDEPRIDE IN PATIENTS WITH SCHIZOPHRENIA AND CONTROLS

The usefulness of I-123-epidepride as a single photon emission compute d tomography (SPECT) scan D-2 receptor ligand was examined in vivo in 13 medicated patients with schizophrenia and age- and sex-matched norm al controls. To establish the effect of endogenous dopamine on I-123-e pidepride binding, 4 of the 13 controls also received 20 mg D-amphetam ine. The results showed that I-123-epidepride had high specific bindin g to the striatum in both patients with schizophrenia and normal contr ols. There was a trend for the total striatal binding of medicated pat ients with schizophrenia, as measured by total basal ganglia:frontal c ortex (TBG:FC) ratios, to be less than the binding of controls (P = 0. 053), This trend confirms previous work showing that antipsychotic med ication decreases the number of D-2 receptors available for binding to the radioligand, Interestingly, there was also a significant relation ship between I-123-epidepride binding ratios and global functioning sc ales (Global Assessment of Functioning scale [GAF]) for schizophrenia (r = 0.56, P = 0.045), although there was no such relationship with th e Brief Psychiatric Rating Scale (BPRS), In addition, our results show ed that amphetamine-induced dopamine release did not alter I-123-epide pride binding, confirming the high specific binding of I-123-epideprid e to the D-2 receptor, We conclude that I-123-epidepride appears to be a very useful SPECT ligand for imaging the D-2 receptor.