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Abstract:
The present study was design to test the hypothesis of a deviant dopaminergic activity in
schizophrenia by using the positron emission tomography (PET) technique (GE 2048-15B Plus
camera) and 11C-labelled L-DOPA as the tracer, which enables calculation of the rate of
synthesis (‘utilization’) of dopamine in different brain regions. Twelve first-admitted and
never-treated patients with a DSM-IV diagnosis of schizophrenia (10 men and 2 women) were
included. Their mean age was 31.6 years. Controls were 10 healthy volunteers (8 male and 2
female) with a mean age of 33 years. Scanning began immediately after injection of
11C-L-DOPA and continued for 60 min. A patlak plot was calculated for each individual,
giving the K3 value, which indirectly reflects the enzymatic utilization of L-DOPA and
indirectly the synthesis rate for dopamine. The data showed no lateralization for any brain
region tested, either in controls or in schizophrenic patients. However, when compared with
healthy controls, a significantly increased synthesis of dopamine was found in the putamen
(K3, 1.75 versus 1.59, P = 0.01) and in the caudatus (K3, 1.72 versus 1.50, P=0.002).
Further, a significantly increased K3 was also seen in the medial prefrontal cortex in
schizophrenic patients (K3, 0.84 versus 0.70, P=0.014). The present results indicate an
increased synthesis of dopamine in certain brain areas, most interestingly in the frontal lobe, in schizophrenia.