Objective: To review the accumulated literature on the efficacy, safety and predictors of response for repetitive transcranial magnetic stimulation (rTMS) in the treatment of depression.
Methods: A descriptive review of the more than 25 published sham-controlled rTMS studies in depression was undertaken, focusing on reported meta-analyses as well as individual trial reports. Potential determinants of efficacy were examined, including the form of shams employed, stimulation parameters and clinical features.
Results: There is now clear evidence for the statistical superiority of left-prefrontal high frequency rTMS compared with sham therapy. However, the clinical benefits are marginal in the majority of reports. There is also still considerable uncertainty concerning the optimal stimulation parameters. Those clinical features which appear to be associated with greater response include younger age, lack of refractoriness to antidepressants and no psychotic features.
Conclusions: Current studies confirm statistical efficacy, but insubstantive clinical benefit. Large multicentre studies currently underway should clarify if rTMS should be approved by regulatory agencies for widespread clinical availability. Furthermore, there is a need to clarify the preferred parameters for administering this treatment.