DOPAMINE D-2 RECEPTOR DENSITY ESTIMATES IN SCHIZOPHRENIA - A POSITRONEMISSION TOMOGRAPHY STUDY WITH C-11 N-METHYLSPIPERONE

Positron emission tomography (PET) with C-11-N-methylspiperone as the radioligand was carried out in 25 chronic schizophrenic patients to de termine dopamine D-2 receptor density estimates in the corpus striatum . The sample included 18 neuroleptic-naive and 7 neuroleptic-free pati ents. Dopamine D-2 receptor density estimates (B-max) were obtained us ing a two-scan/ four-compartment model. The B-max estimates for the en tire group (33.39 +/- 3.43 pmole/g) were significantly elevated when c ompared with estimates for the control group (B-max = 15.63 +/- 2.38). The B-max values for the entire group of schizophrenic patients showe d a significant decline as a function of age. The B-max values were si gnificantly related to duration of illness (y = 13.2 + 10.3795x - 0.79 31x(2); r = 0.48). Thirteen patients and seven control subjects were a dded to our original publication sample (Wong et al., 1986c). The pati ents' B-max values, when adjusted for age and sex effects, were signif icantly different compared with those of control subjects. Clinical da ta from the entire group were compared with published data from other research groups that have estimated dopamine D-2 receptor density usin g different radioligands and different methods of data analysis. Compa risons of the clinical characteristics of the published studies show s ignificant differences in patient populations, suggesting that discrep ancies among published studies may reflect, in part, heterogeneity amo ng groups of schizophrenic patients. The D-2 receptor abnormality desc ribed in this study may be a late manifestation of disease, and the im plications of this observation are discussed.