Drug-naive schizophrenia: The dopamine connection.

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 naïve 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.

Citation source: Molecular Psychiatry 2003 Volume 8, number 4, pages 453-455.

For further information on this work, please contact Prof. Jari Tiihonen M.D., Ph.D., Department of Psychiatry, University of Helsinki, PO Box 320, FIN-00029 HUCH, Finland; Tel. 358-9-471-81-200; Fax: 358-9-471-81-313; E-mail: jari.tiihonen@hus.fi
ARTICLE: "Extrastriatal dopamine D2/3 receptor density and distribution in drug-naive schizophrenic patients"
AUTHORS: Heli Tuppurainen, Jyrki Kuikka, Heimo Viinamäki, Minna
Husso-Saastamoinen, Kim Bergström, and Jari Tiihonen
Department of Psychiatry, University of Kuopio, PO Box 1777, FIN-70211 Kuopio, Finland; Department of Clinical Physiology, Kuopio University Hospital, PO Box 1777, FIN-70211 Kuopio, Finland; Department of Forensic Psychiatry, University of Kuopio, Niuvanniemi Hospital, Kuopio, Finland; Department of Psychiatry, University of Helsinki, Finland.

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