Since the introduction of chlorpromazine in psychiatry in 1952, all antipsychotic drugs with proven efficacy have been dopamine (DA) D2 receptor antagonists. It has been suggested that positive schizophrenic symptoms (such as hallucinations) are associated with increased subcortical DA neurotransmission, and negative and cognitive symptoms with impaired mesocortical DA function. Studies on striatal D2 receptor densities in drug-naive schizophrenic patients have indicated that deviation in D2 density is larger among patients vs. controls, and although some patients have markedly elevated D2 levels, the D2 densities do not differ substantially at group level. Although DA neurotransmission in basal ganglia may be more important for motor functions rather than for emotions and behavioral symptoms, D2 binding studies have previously concentrated in the striatum, because there have been no suitable in vivo -ligands available for measuring extrastriatal D2 receptor binding. The aim of this study was to test the hypothesis that extrastriatal D2/3 density in temporal and cingulate cortex is lower among drug naive schizophrenic patients when compared with matched controls.

The results indicate that in drug-naive schizophrenic patients the extrastriatal dopamine D2/3 receptor density is markedly decreased. The authors also observed negative correlations between D2/3 receptor density and age among controls, and between D2/3 density and negative and general psychopathological symptom scores among patients. These results support the previous hypothesis on dysfunction of mesocortical dopamine function behind the cognitive and negative symptoms in schizophrenia.

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Contact: Aimee Midei
molecularpsychiatry@mednet.ucla.edu
310-206-6739
Molecular Psychiatry
12-May-2003

Page: 1
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