Increase of striatal dopamine transmission in first episode drug-naive schizophrenic patients as demonstrated by [¹²³I]IBZM SPECT

Abstract 

Acute psychotic exacerbation in schizophrenia is associated with a “striatal hyperdopaminergic state”. The aim of this investigation was to test this hypothesis by assessing striatal dopamine D₂ receptor availability using single photon emission computed tomography (SPECT) and the specific D₂ radioligand [¹²³I]IBZM in first episode, drug-naïve, schizophrenic patients and compare it with that in healthy control subjects. Additionally, D₂ radioligand binding was correlated with the extent of psychopathology assessed by specific rating scales including Positive and Negative Syndrome Scale (PANSS). Twenty-three acutely ill, treatment-naïve, inpatients suffering from a first acute psychosis were studied. Patients were assigned to a psychopathological syndrome-type according to PANSS positive and negative subscale results. The PANSS items delusions, conceptual disorganization, and hallucinatory behaviour were chosen to assess the extent of the acute psychotic syndrome. Patients showed a significantly lower specific [¹²³I]IBZM binding compared with the control group. Positive and negative syndrome type patients differed significantly with respect to specific IBZM binding. There was a significant negative correlation between IBZM binding and the PANSS item ‘hallucinatory behaviour’ in patients with pronounced positive symptoms. The data obtained show a significant difference between acute psychotic patients, patients with predominant negative syndrome, and healthy controls, according to the concept of a “hyperdopaminergic state” in psychotic exacerbation.

Keywords: Striatal dopamine D₂ receptor, Acute psychotic syndrome, Hallucinations