Methods: PET was performed in 12 drug;free (10 drug-naive) psychotic schizophrenic patients and 10 healthy volunteers matched for age and gender using C-11-labelled L-DOPA as the tracer The time-radioactivity curve from occipital cortex (located within Brodman area 17 and 18) was used as input function to calculate L-DOPA influx rate, K-i images, that were matched to a common brain atlas. A significant overall increase of the K-i values was found in the schizophrenic group as compared with healthy controls.

Results: In particular, significantly higher K-i were found in the schizophrenic patients compared to the controls in the caudate nucleus, putamen and in parts of medial prefrontal cortex (Brod 24). The K-i value reflect an increased utilization of L-DOPA, presumably due to increased activity of the amino acid decarboxylate enzyme.

Conclusions: The results indicate that the synthesis of dopamine is elevated within the striatum and parts of medial prefrontal cortex in schizophrenia. Biol Psychiatry 1999;46:681-688 (C) 1999 Society of Biological Psychiatry.