Frontal Dopamine D2/3 Receptor Binding in Drug-Naive First-Episode Schizophrenic Patients Correlates with Positive Psychotic Symptoms and Gender

BackgroundThe aim of the study was to examine extrastriatal dopamine D2/3 receptor binding and psychopathology in schizophrenic patients, and to relate binding potential (BP) values to psychopathology.MethodsTwenty-five drug-naive schizophrenic patients and 20 healthy controls were examined with single-photon emission computerized tomography (SPECT) using the D2/3-receptor ligand [123I]epidepride.ResultsIn the hitherto largest study on extrastriatal D2/3 receptors we detected a significant correlation between frontal D2/3 BP values and positive schizophrenic symptoms in the larger group of male schizophrenic patients, higher frontal BP values in male (n = 17) compared to female (n = 8) patients, and – in accordance with this – significantly fewer positive schizophrenic symptoms in the female patients. No significant differences in BP values were observed between patients and controls; the patients, however, had significantly higher BP in the right compared to the left thalamus, whereas no significant hemispheric imbalances were observed in the healthy subjects.ConclusionsThe present data are the first to confirm a significant correlation between frontal D2/3 receptor BP values and positive symptoms in male schizophrenic patients. They are in agreement with the hypothesis that frontal D2/3 receptor activity is significant for positive psychotic symptoms. Additionally, the data support a thalamic hemispheric imbalance in schizophrenia.