December 3, 2004
MR spectroscopy may become the definitive imaging test to diagnose bipolar disease, a serious mental illness affecting more than two million Americans.
IN A SCIENTIFIC paper session yesterday, John D. Port, M.D., Ph.D., presented what he called the largest study of drug and medication-free bipolar patients ever performed. Dr. Port is a consultant and assistant professor of radiology at the Mayo Clinic in Rochester, Minn. His team used MR spectroscopy of the brain to identify significant differences between the brain chemistries of people with and without bipolar disorder.
"Psychiatric illness in general is one of the most challenging areas of medicine to diagnose," Dr. Port said. "There are no physical signs of the illness, no tests to confirm it. It often takes years of meeting with a psychiatrist to get a diagnosis. Nobody ever puts the whole picture together. As a result, those with bipolar disorder are a very underserved population."
The researchers studied 21 patients with bipolar disorder who were not taking medications or drugs. They also found 21 people without the disorder who were the same age, sex and used the same right- or left-dominant hand. Study participants ranged in age from 18 to 55 and included 26 women and 16 men. The scans of participants' brains were completed in about an hour. In the bipolar group, there was a mix of those in manic and depressed states.
MR spectroscopy allows researchers to analyze chemical properties of brain tissue. They studied 60 to 70 regions of the brain, gathering thousands of points of data. They also analyzed the brain's metabolites, chemical substances produced as the body processes energy.
The group found the metabolite balance in bipolar patients was significantly different than that of the control group in brain areas responsible for behavior, movement, vision, reading and sensory information.
Dr. Port said the patterns displayed created a "fingerprint" of the disease. He also reported findings never seen before in the parietal white matter of the brain.
"This is an area not thought at all to be involved in psychiatric disease," he explained. "We looked at it just because we wanted a control area, but we did find differences. Another innovation is that this is the first time anyone's used a 3 T longbore scanner versus a 1.5 T scanner.
Dr. Port explained that the 3 T scanner allows much larger samples of tissue. The researchers were able to obtain two slices or views of each participant's brain. They collected more than 2,500 voxels represented in images by tiny colored squares which the team turned into chemical maps of the brain tissue.
Dr. Port admitted there is a long way to go before physicians can scan patients and diagnose mental illnesses. "The ultimate goal is to look at someone we think is bipolar, but we don't know, and be able to use imaging techniques to help us make the diagnosis."
Additionally, Dr. Port said it was important for this study to use patients with no exposure to lithium, the drug traditionally used to treat bipolar disease, or medications of any kind. "We wanted to see bipolar disease in its native state," he said. "It would be nice if we could extend this study with a treatment arm, put patients on lithium and scan them a couple of days after starting, then weeks and months later."
Left untreated, bipolar episodes typically become more frequent and more resistant to medication. Each year, approximately 30,000 depressed individuals commit suicide, according to the National Institute of Mental Health.
Copyright ©2004 Radiological Society of North America, Inc (RSNA)
NAMI wishes to thank the Radiological Society of North America, Inc. for permission to reprint this article.
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