Decreased dopamine D-2 receptor binding in the anterior cingulate cortex in schizophrenia

Background: The clinical efficacy of dlopamine D, receptor antagonism on the psychotic symptoms of schizophrenia has been widely demonstrated. However, most in vivo imaging studies have not been able to detect significant changes in striatal D-2 receptors in schizophrenia. On the other hand, a number of studies have reported abnormalities in the cerebral cortex of schizophrenia. The aim of this study was to examine the extrastriatal D-2 receptors of patients with schizophrenia. Methods: Eleven drug-naive male patients with schizophrenia were examined with positron emission tomography using carbon 11-labeled FLB 457. Symptoms were assessed using the Brief Psychiatric Rating Scale. Eighteen healthy controls were used for comparison. Region-of-interest analysis was performed using the reference tissue method, and binding potential (BP) was used for the index of dopamine D-2 receptor binding. Results: The BP value was significantly lower, by about 12.5%, in the anterior cingulate cortex in drug-naive patients with schizophrenia than in healthy controls, A significant negative correlation was observed between BP in the anterior cingulate cortex and the positive symptom score on Brief Psychiatric Rating Scale. Conclusions: The lower BP values indicate fewer D-2 receptors in the anterior cingulate cortex in patients with schizophrenia. Alterations in D-2 receptor function in the extrastriatal region may underlie the positive symptoms of schizophrenia.