Dopamine D2 receptor density estimates in schizophrenia: A positron emission tomography study with11C-N-methylspiperone

Abstract Positron emission tomography (PET) with 11 C- N -methylspiperone as the radioligand was carried out in 25 chronic schizophrenic patients to determine dopamine D 2 receptor density estimates in the corpus striatum. The sample included 18 neuroleptic-naive and 7 neuroleptic-free patients. Dopamine D 2 receptor density estimates ( B max ) were obtained using a two-scan/four-compartment model. The B max estimates for the entire group (33.39 ± 3.43 pmole/g) were significantly elevated when compared with estimates for the control group ( B max = 15.63 ± 2.38). The B max values for the entire group of schizophrenic patients showed a significant decline as a function of age. The B max values were significantly related to duration of illness (y = 13.2 + 10.3795x - 0.7931x 2 ; r = 0.48). Thirteen patients and seven control subjects were added to our original publication sample (Wong et al., 1986 c ). The patients' B max values, when adjusted for age and sex effects, were significantly different compared with those of control subjects. Clinical data from the entire group were compared with published data from other research groups that have estimated dopamine D 2 receptor density using different radioligands and different methods of data analysis. Comparisons of the clinical characteristics of the published studies show significant differences in patient populations, suggesting that discrepancies among published studies may reflect, in part, heterogeneity among groups of schizophrenic patients. The D 2 receptor abnormality described in this study may be a late manifestation of disease, and the implications of this observation are discussed.