Striatal D-2/3 Binding Potential Values In Drug-Naive First-Episode Schizophrenia Patients Correlate With Treatment Outcome

One of best validated findings in schizophrenia research is the association between blockade of dopamine D-2 receptors and the effects of antipsychotics on positive psychotic symptoms. The aim of the present study was to examine correlations between baseline striatal D-2/3 receptor binding potential (BPp) values and treatment outcome in a cohort of antipsychotic-naive first-episode schizophrenia patients. Additionally, we wished to investigate associations between striatal dopamine D-2/3 receptor blockade and alterations of negative symptoms as well as functioning and subjective well-being. Twenty-eight antipsychotic-naive schizophrenia patients and 26 controls were included in the study. Single-photon emission computed tomography (SPECT) with [I-123] iodobenzamide ([I-123]-IBZM) was used to examine striatal D-2/3 receptor BPp. Patients were examined before and after 6 weeks of treatment with the D-2/3 receptor antagonist amisulpride. There was a significant negative correlation between striatal D-2/3 receptor BPp at baseline and improvement of positive symptoms in the total group of patients. Comparing patients responding to treatment to nonresponders further showed significantly lower baseline BPp in the responders. At follow-up, the patients demonstrated a negative correlation between the blockade and functioning, whereas no associations between blockade and negative symptoms or subjective well-being were observed. The results show an association between striatal BPp of dopamine D-2/3 receptors in antipsychotic-naive first-episode patients with schizophrenia and treatment response. Patients with a low BPp have a better treatment response than patients with a high BPp. The results further suggest that functioning may decline at high levels of dopamine receptor blockade.