Dual-isotope SPECT imaging of striatal dopamine: A comparative study between never treated and haloperidol treated first episode schizophrenic patients

Abstract Background: The aim of this investigation was to evaluate the striatal dopamine transporter (DAT) and D2 receptor availability by dual-isotope SPECT imaging in first episode schizophrenic patients in the never treated and haloperidol treated state compared to healthy control persons. Methods: Two groups of each 12 acutely ill drug naive inpatients suffering from a first acute schizophrenic episode and 12 healthy control persons were analyzed. One patient group was treated with haloperidol for a 14 days steady state treatment. The other group underwent the SPECT protocol in the drug naïve state. The dual-isotope SPECT protocol used combined application of [99mTc]TRODAT-1 and [123I]IBZM. Psychopathology was assessed in the patient group by specific scales including PANSS. Results: With respect to D2 availability to the specific radioligand, drug naïve patients did not differ to the control group while there was a significant reduction of D2 availability in the haloperidol treated compared to the drug naïve patients and the healthy control group. Availability of the DAT was significantly reduced in the treated patients, too. DAT availability correlated positively with the haloperidol dose. Discussion: The data obtained with the new dual-isotope SPECT technique reveal a direct effect of haloperidol not only postsynaptically but at the at the presynaptic DAT, too.