Research Review

Magnetic Stimulation Scores Modest Success as Antidepressant

Some depressed patients who don't respond to or tolerate antidepressant medications may benefit from a noninvasive treatment that stimulates the brain with a pulsing electromagnet, a study suggests.  This first industry-independent, multisite, randomized, tightly controlled trial of repetitive transcranial magnetic stimulation (rTMS) found that it produced significant antidepressant effects in a subgroup of patients, with few side effects.  

Active rTMS treatment accounted for remissions in 14% of antidepressant-resistant patients actively treated, compared to about 5% for a simulated treatment. Mark George, MD, of the Medical University of South Carolina, and colleagues, report on their findings in the Archives of General Psychiatry.

Following a decade and a half of studies yielding mixed results, the FDA cleared an rTMS device for treatment of mildly treatment-resistant depression in 2008, based on data submitted by the manufacturer. The field has been awaiting the results of the NIMH-funded multisite trial to provide more definitive evidence of efficacy.

A sample of 190 patients who had previously failed to respond to antidepressant medications received at least three weeks of randomized, controlled magnetic stimulations on weekdays for three weeks, with the rTMS magnet aimed at their brain's left prefrontal cortex. Those who showed improvement received up to an additional three weeks of such blinded treatment.  

Thirteen (14%) of 92 patients who received the active treatment achieved remission, compared to 5 (about 5%) of 98 patients who received the simulation treatment. Patients who received active rTMS were significantly more likely to reach remission, particularly if they had been moderately, rather than severely, treatment resistant. The remission rate climbed to nearly 30% in an open-label phase of this study in which there was no simulation control. George said this is comparable to rates seen in the STAR*D medication studies. However, the researchers noted that "the overall number of remitters and responders was less than one would like with a treatment that requires daily intervention for three weeks or more, even with a benign side effect profile."

Since the rTMS treatment did not trigger any seizures or notable side effects, the researchers propose that higher levels of magnetic stimulation be used in future studies, as evidence suggests antidepressant effects of such stimulation are dose-dependent. Higher remission rates might also be attainable if rTMS were combined with medications, they suggested.

— National Institutes of Health