rTMS Effective in Major Depression
Mark George from the Medical University of South Carolina presented a sham-controlled, multi-site, randomized trial of repeated transcranial magnetic stimulation (rTMS) in 199 antidepressant-free patients with unipolar non-psychotic major depression. The rTMS was delivered to the left prefrontal cortex for 37.5 minutes at 120% of motor threshold (MT), with a 10 Hz, four-second train duration and 26-second inter-train interval, yielding 3000 pulses/session, with a figure-of-eight solid core coil. Compared with the sham treatment (which plays the same role a placebo would in a drug trial), active rTMS had a significant effect (p = .015), with 14% of patients remitting on the treatment compared with 5% on the sham procedure. Thus, the odds of attaining remission (the primary outcome measure) were several times greater with active rTMS than sham.
The number needed to treat (NNT), a measure of the number of patients who would need to be treated with active rTMS in order to get one more responder compared to the number of responders seen on sham rTMS (the smaller the number, the more effective the treatment) was 12. However, as in other previous studies, most of the remitters had prior low antidepressant-rated degrees of treatment resistance. When the blind study was complete and patients were openly given rTMS treatments (a practice known as open label extension), approximately 30% of the patients from each condition were able to achieve remission.
EDITOR’S NOTE: This large study, sponsored by NIMH rather than the pharmaceutical industry, confirms previous industry-related findings that active rTMS is more effective than sham in the treatment of major depressive disorder. These data also conform to recent meta-analyses of many smaller studies indicating that high intensity rTMS treatment is clinically effective for major depression. In prior rTMS studies, those with bipolar depression appeared to respond at about the same rate as those with unipolar illness, suggesting the possibility that these findings might also generalize to those with bipolar disorder, although this remains to be studied more systematically.
This study showed that patients with greater degrees of initial treatment resistance had less optimal outcomes to active rTMS. Some studies also show that electro-convulsive therapy (ECT) decreases in effectiveness in those with greater degrees of treatment-resistance. Response rates to ECT are approximately 40-50% in those with high degrees of treatment-resistance compared with 60-80% in those without. The rTMS data suggest that the treatment as studied may be a useful alternative to antidepressants for some patients with major depression, but it may not be an optimal approach for those with the highest degrees of treatment resistance. Further studies are warranted in patients with high treatment resistance in order to define optimal stimulation parameters that may be more successful for them.
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