LONDON, Feb 12 - Scientists have found more evidence that schizophrenia has a physical basis, the weekly science magazine Nature reported. Japanese researchers said that by using advanced scanning technology known as positron emission tomography (PET) they had shown schizophrenics had significant deficiencies of a key brain receptor which affect peoples' moods and other mental processes.
Schizophrenia has long been thought to involve changes in the way dopamine, a chemical neurotransmitter which transmits impulses in the brain, affect these receptors. Basic research supporting this came from the fact that drugs effective in treating psychosis interacted with a key group, known as D2, of these dopamine receptors. Attempts to find changes in the amount of D2 receptors in schizophrenics' brains have been inconclusive. But the Japanese researchers, led by Yoshiro Okubo of the Tokyo Medical and Dental University School of Medicine, said their PET studies had shown significant deficiencies of similar receptors, known as D1, in the brains of schizophrenic patients.
"This reduction was related to the severity of the negative symtoms, for instance emotional withdrawal," they wrote. The researchers said this suggests that drugs which target these D1 receptors may be helpful in treating the negative symtoms of schizophrenia, a mental disease frequently accompanied by delusions and retreat from social life.
In an analysis of the research, Eric Nestler of the Yale School of Medicine said the research was part of a more sophisticated view of the illness which is gradually emerging. Now, he wrote, researchers will have to determine whether schizophrenia involved either the loss of cells transmitting nerve impulses, called neurons, in the outer part of the brain or sustained impairment in the activity of existing neurons. "Sophisticated neurobiological hypotheses of schizophrenia are now emerging which define the critical directions for future research," Nestler said.
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Relevant Web sites to the above story:
Nature Magazine - http://www.nature.com
Tokyo Medical and Dental University School of Medicine http://www.tmd.ac.jp/TMDU-e/TMDU_eHomePage.html (Note: this sit is in Japan so it takes a while to respond)
The NeuroScientist - Online Edition http://www.theneuroscientist.com/ (Eric Nestler of The Yale School of Medicine has been published here)
Neuron - The Online Magazine - http://www.cell.com/neuron/index.html
Yale School of Medicine: http://www.med.yale.edu/