The prognostic value of dopamine receptor occupancy by [123I]IBZM-SPECT in schizophrenic patients treated with quetiapine.

Background: In the present study D2 receptor occupancy was investigated in quetiapine treated schizophrenic patients for the detection of a relationship between the scintigraphic pattern and clinical signs and symptoms.

Material And Methods: In 10 schizophrenic patients [123I]IBZM-SPECTs were performed during the introduction of quetiapine therapy (600-800 mg/day) and during a lower maintenance dose (200-400 mg/day). The patients' clinical follow-up was continued for 1 year. For the evaluation of SPECT images, visual interpretation was performed and striatum/occipital lobe (S/O) activity ratio was calculated.

Results: The initial striatum/occipital ratio was significantly higher in patients with relapse compared to the others (1.86 +/- 0.17, 1.53 +/- 0.15, p < 0.01). The decreasing striatum/occipital ratio (increasing D2 receptor occupancy) on the 2nd SPECT was a predictive factor for the relapse.

Conclusions: D2 receptor occupancy and its changes during quetiapine therapy were related to the prognosis of the treatment efficacy.