NEW YORK, Nov 08 (Reuters Health) -- Risperidone, a relatively new psychiatric drug, appears to boost the function of an area of the brain that plays an important role in thought processes such as short-term (or "working") memory in schizophrenics.
The finding is "direct evidence" that risperidone increases activity in this area of the brain, called the prefrontal cortex, in schizophrenic patients, according to a report published in the November 9th issue of the Proceedings of the National Academy of Sciences.
The study "may open a new era of research on drugs for schizophrenia," according to a statement issued by the journal's editors.
Previous work with schizophrenic patients has shown reduced blood flow to the frontal areas of the brain during tasks that demand working memory, according to Garry D. Honey from the Institute of Psychiatry in London, UK, and associates.
In the first study of its kind, the investigators used functional MRI -- a special kind of brain imaging -- to measure blood flow to various areas of the brains of 10 schizophrenic patients taking traditional antipsychotic drugs, 10 schizophrenic patients taking risperidone (a newer, atypical antipsychotic), and 10 healthy volunteers. The brain scans were performed while the patients were busy taking a simple test of working memory.
Switching patients from typical antipsychotic drugs to risperidone was associated with increased blood flow to three areas near the front of the brain involved in working memory, the results indicate. Increased blood flow is believed to correlate with increased activation of those brain areas.
Accompanying these improvements in regional brain function were slight improvements in the clinical status of the schizophrenic patients taking risperidone, the authors report.
Though the scientists are uncertain of the mechanism by which risperidone enhances brain function, they believe its beneficial effects on dopamine and serotonin levels may account for the improvements. Dopamine and serotonin are important chemical messengers in the brain.
The investigators conclude not only that risperidone enhances the function of brain areas associated with working memory but also that functional MRI can be useful in understanding the effects of drugs on the brain.
