power to reduce auditory hallucinations
Psychiatric patients who continue to hear voices despite medication experience relief when an area of the brain responsible for speech perception is stimulated with magnetic waves, Yale researchers have found.
The results of the repetitive transcranial magnetic stimulation (rTMS) study, published this month in the Archives of General Psychiatry, were an improvement over clinical outcomes reported for an earlier study where the magnetic stimulation was applied for a shorter period of time.
Dr. Ralph Hoffman, associate professor of psychiatry at the School of Medicine and lead author of the current study, says the patients with schizophrenia received a total of 132 minutes of total stimulation over a nine-day period. In the earlier study, the patients received 40 minutes of stimulation over a four-day period.
"We were trying to see if a more extended protocol could obtain more clinically significant improvements," he says. "We did see greater and more sustained improvements in reducing hallucinations as well as an improvement in the patients' overall clinical well being."
There were 24 patients enrolled in the study. Half were randomly assigned to receive the rTMS and half underwent a sham or placebo form of rTMS. Hoffman is still enrolling patients in the ongoing study. Currently 49 patients have completed the protocol with a similar pattern of results.
Auditory hallucinations are reported by 50% to 70% of patients with schizophrenia. A large percentage of patients say the voices they hear are highly distressing, especially when the verbal content is negative or intrusive. Auditory hallucinations disrupt social functioning and are associated with acts of violence and suicide.
In about 25% of cases, the auditory hallucinations are not minimized or controlled by medication. The study enrolls patients who are experiencing medication resistant auditory hallucinations at least five times a day.
Hoffman and his colleagues conducted neuroimaging studies of patients during periods when they were experiencing auditory hallucinations and found disturbances appearing in the right and left superior temporal cortex areas, which involve speech perception.
During the rTMS treatment, the patient reclines in a chair and a coil is placed on the scalp over the area of the brain that is believed to be responsible for the auditory hallucinations. Magnetic field pulses, which are delivered once per second, pass undistorted through scalp and skull, inducing electrical currents that briefly activate neurons beneath the coil. Other studies suggest that such stimulation produces prolonged reductions in neural excitability without damaging neurons themselves. During the trial, patients do not know whether they are receiving real or sham stimulation.
Reductions of auditory hallucinations were determined by interviewing patients before and after rTMS by a research psychologist who also did not know the type of stimulation given. Much greater improvements in patients' symptoms were observed following real stimulation compared with sham stimulation.
The treatments, Hoffman says, appeared to be well tolerated by the patients. Some reported mild headaches, which were relieved with acetaminophen. Others reported lightheadedness lasting several minutes. Duration of treatment affects ranged from one week up to a full year.
Also involved in the study were Keith Hawkins, Ralitza Gueorguieva, Dr. Nash Boutros, Dr. Fady Rachid, Kathleen Carroll, and Dr. John Krystal, all of the Department of Psychiatry.
-- By Jacqueline Weaver
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