BLOODLESS BRAIN "BIOPSY" GIVES ACCURATE VIEW OF BRAIN CHEMISTRY
COLUMBUS, Ohio -- New research shows that a safe, noninvasive technology related to magnetic resonance imaging (MRI) can provide accurate and valuable information about the brain chemistry of psychiatric patients.
Once developed further, this technology -- called magnetic resonance spectroscopy (MRS) -- could revolutionize both psychiatric diagnosis and treatment, scientists say.
MRS may someday be used as a diagnostic tool for mental illness, a means for developing more appropriate treatment and a resource for developing new medications, said Henry Nasrallah, chairperson of psychiatry at Ohio State University.
In a pilot study, Nasrallah and several colleagues used proton MRS to study brain chemistry involved in schizophrenia.
They found that the concentration of the neurochemical N-acetyl aspartate (NAA), as measured by proton MRS, was significantly lower in the right hippocampus of schizophrenics than in people not suffering from the disease.
NAA is a chemical compound found mainly in brain cells, or neurons; the hippocampus is part of the brain's temporal lobe and
part of the limbic system, which controls a variety of emotional and memory functions.
"Recent postmortem and brain imaging studies strongly suggest that the hippocampus is slightly smaller in schizophrenics compared with healthy people," Nasrallah said. "Our neurochemical results are consistent with the anatomical findings. What's more important, however, is that our results provide a window on the metabolism and chemistry of the brain. They're like the results of a live brain 'biopsy' -- a 'biopsy' done without ever touching the brain."
Psychiatrists have learned many things about mental illness by studying structural abnormalities in the brains of patients with schizophrenia, manic depressive illness and depression, Nasrallah said.
"This technology allows us to take things further, to start mapping the chemical content of the brain, not just the structural anatomy," Nasrallah said. "Chemical content is of great importance to us in psychiatry because most of the disorders we treat are chemical disorders. Chemical disorders can be treated."
Nasrallah conducted this research with Thomas E. Skinner, research scientist in psychiatry; Petra Schmalbrock, research scientist in radiology; and Pierre-Marie Robitaille, associate professor of radiology, all from Ohio State. The group's work was published in a recent issue of the British Journal of Psychiatry .
For their study, Nasrallah and his colleagues used proton MRS to measure the NAA in the hippocampus regions of 22 individuals. Eleven of the 22 were clinically stable patients diagnosed with chronic schizophrenia. The other 11 were mentally healthy volunteers. The two groups were similar in gender, age and educational levels.
Results showed that the average NAA intensity in the right hippocampus region of schizophrenic patients was 26 percent lower than that of normal volunteers. However, the average NAA intensity in the left hippocampus region of schizophrenics was somewhat lower but not significantly different from that of normal volunteers.
"It's possible that with a larger sample size, both the left and right limbic temporal lobes in schizophrenia would show a significant reduction in NAA," Nasrallah said. "In fact, since our article was submitted, its findings have been replicated by other scientists on both the left and right sides."
Nasrallah said these findings, and those of ongoing studies, will very likely have major implications for the field of psychiatry.
"There are many more studies being done now, some using different chemicals, some using a different type of MRS," he said. "Eventually, MRS may be a procedure to help diagnose a certain mental illness and differentiate it from other disorders. There are a lot of psychiatric disorders that resemble each other. It helps to have an objective biological measure to distinguish the specific diagnosis."
Proton MRS will very likely be used by psychiatrists as a predictive tool in the early stages of mental illness, Nasrallah said.
"For example, we'll be able to see if there's a relationship between a symptom of schizophrenia, such as hearing voices, and the chemical composition of certain brain regions," he said. "Knowing that, we'll be able to predict certain patterns of behavior in patients."
Proton MRS may also result in the development of new treatments for patients, he said.
"In most schizophrenic patients, the brain's anatomical changes are static, so the disease doesn't become progressively worse," he said. "However, about 10 to 15 percent of patients show almost progressive degeneration. Proton MRS may be able to tell us if a patient's schizophrenia is degenerative or not. We may be able to identify one group that has degenerative schizophrenia and one group that doesn't and therefore treat each group more appropriately."
Perhaps most important, Nasrallah said, proton MRS may lead to the development of new and more effective medications for serious mental illnesses.
"Some new medications have shown promise in reactivating the 'lost' functions associated with schizophrenia, such as inability to plan, pay attention or process information," he said. "With MRS, we may be able to monitor what happens with these medications -- specifically, what parts of the brain are being activated and changed by them. That's going to lead us to an understanding of why these medications work and how we can develop even better ones."
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Contact: Henry Nasrallah, (614) 293-8283
Written by Kelly Kershner, (614) 292-8308