Jan. 1, 2004 Belmont, MA -- A rarely used combination of magnetic fields generated with a conventional MRI scanner immediately and significantly improved the mood of subjects with bipolar disorder, according to researchers at McLean Hospital in Belmont, Mass.
"This is a very unusual MRI exam used for the first time in this study. We were surprised at our good fortune in discovering this effect and we are excited about the initial findings," says Michael Rohan, imaging physicist in McLean's Brain Imaging Center.
The study published in the January 1 issue of the American Journal of Psychiatry had a surprising start. Rohan explains, "We were using MRI to investigate the effectiveness of certain medications in bipolar patients and noticed that many came out of the MRI feeling much better than when they went in. We decided to investigate further."
Researchers theorized that one type of magnetic pulse they were using was having the positive effect. "This was purely accidental. We just happened to use this set of magnetic gradients, which we think somehow matches the natural firing rhythm of brain cells." Technically this kind of scan is called EP-MRSI, or Echo-Planar Magnetic Resonance Spectroscopic Imaging.
After realizing they may be observing a real effect, researchers expanded the study to include sham EP-MRSI scans with bipolar subjects, normal EP-MRSI scans in healthy subjects, in addition to EP-MRSI scans in bipolar subjects.
The results showed 23 out of 30 bipolar subjects who received the actual EP-MRSI tests reported mood improvement, indicating a 77 percent response rate. In addition, subjects who were not on medication showed even greater response (100 percent) compared to the response rate of those on medication (63 percent). These results were not seen in the other two groups, those with bipolar disorder receiving sham EP-MRSI and healthy individuals receiving EP-MRSI.
The authors note that one other test using electromagnetic energy has previously shown some positive effect in subjects with depression. This rTMS, or repetitive transcranial magnetic stimulation test, was originally developed in the 1980s to test nerve function. It uses a magnetic device that is held next to the head. Studies using this treatment for depression typically result in a 40 percent to 50 percent response rate. However, the McLean authors note that this test uses a much stronger magnetic field that can be painful to the patient.
The magnetic field the McLean researchers are using is approximately 200 times weaker than rTMS and like a standard MRI, the patients feel nothing. Researchers are currently developing a tabletop device that delivers the precise magnetic field originally used in this study with the MRI scanner.
Downsizing the machinery is expected to prove more efficient and cost effective in the long run.
"We are also planning a much larger clinical study using this smaller device to further test this effect," adds Rohan. Researchers believe one day such a device may be used during perhaps a 20-minute nap at a doctor's office.
McLean Hospital is the largest psychiatric affiliate of Harvard Medical School and maintains the largest research program of any private psychiatric hospital in the U.S.
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