Decreased binding of [11C]NNC112 and [11C]SCH23390 in patients with chronic schizophrenia

AimsAbnormality of cognitive function in schizophrenia has been suggested to be related to dopamine D1 receptor. However, the results of previous positron emission tomography (PET) studies of dopamine D1 receptor in schizophrenia were not consistent.Main methodsIn this study, six patients with schizophrenia in severe residual phase with chronic antipsychotic treatment and twelve healthy age-matched controls participated. Two different radioligands, [11C]NNC112 and [11C]SCH23390, for dopamine D1 receptor were used on the same subjects. Binding of the ligands was measured by PET, and statistical analysis was performed using one-way analysis of covariate (ANCOVA) with age as covariate.Key findingsGood correlations between binding potential values (BPND) and age were observed in all regions of interest (ROIs) with both ligands. ANCOVA with age as covariate of BPND values of all ROIs revealed that the patient group showed significantly lower BPND value compared with the control group in both ligands.SignificanceIn patients with chronic schizophrenia in severe residual phase with chronic antipsychotic treatment, the binding potential values of both ligands were significantly lower in the striatum and cortical regions than those of healthy controls.