Depressed patients who don't respond to antidepressants, or who can't tolerate the medications, might benefit from a non-invasive treatment that stimulates the brain with a pulsing electromagnet, research suggests.
The new study found that daily use of "transcranial magnetic stimulation" appears to help relieve treatment-resistant depression.
Repetitive transcranial magnetic stimulation (rTMS) uses magnetic currents delivered to the prefrontal cortex in the top left front part of the brain. The aim is to jump-start underactive mood-regulating circuitry. While some studies over the last decade and a half of studies have shown the method has potential as a depression treatment, the quality of that research has been questioned.
This study, published in the prestigious Archives of General Psychiatry, was a tightly controlled, industry-independent, randomized controlled trial funded in part by the National Institute of Mental Health in the U.S.
For the study, Dr. Mark S. George, of the Medical University of South Carolina, in Charleston, led a team that recruited 190 patients with depression who were not taking medication. Of them, 92 were randomly assigned to receive rTMS, which involved stimulating the left prefrontal cortex with an electromagnetic coil for 37.5 minutes daily for three weeks.
The other 98 received a sham treatment that mimicked the sensory experience of stimulation using similar scalp electrodes but with the magnetic field blocked.
The researchers found that the depression lifted in 14.1 per cent of those in the magnetic stimulation group, compared with 5.1 per cent in the sham group. That made the odds of achieving remission 4.2 times greater in the rTMS group.
The patients who achieved remission then were given a combination of medications intended to help maintain the treatment effect. Even though all had failed in the past to respond to medications, most remained in remission for several months.
Based on the results of this study, the researchers calculate that for every 12 patients treated with transcranial magnetic stimulation, one would remit from depression.
The benefit of rTMS is that it can be safely administered in a doctor's office with few side effects -- unlike more invasive brain stimulation treatments, such as electroconvulsive therapy. The patients in this study reported few side effects.
"This study should help settle the debate about whether rTMS works for depression," said Dr. George.
"We can now follow up clues suggesting ways to improve its effectiveness, and hopefully further develop a potential new class of stimulation treatments for other brain disorders."
As an indication of how well blinded the study was, at the end of treatment, patients, their treaters and the research evaluators were asked to guess which patients were in the active or treatment group. Only treaters were able to guess at a rate more accurate than chance, and even they were not very confident of their responses.
The Food and Drug Administration in the U.S. cleared an rTMS device for treatment of mildly treatment resistant depression in 2008.
