Safety and efficacy of repetitive transcranial magnetic stimulation in the treatment of depression: a critical appraisal of the last 10 years

Abstract

Depression is a common and debilitating illness, for which alternative treatments are urgently needed. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive and relatively painless experimental technique of altering brain physiology. The authors critically review the evidence for the efficacy, safety and tolerability of rTMS in the treatment of depression based on published data over the last decade. They also discuss studies which have examined relevant clinical, demographic, methodological, and technical parameters that might be implicated in optimizing the antidepressant efficacy of this technique. rTMS depression trials conducted through early 2006 are included in this review, which focuses mainly on the results of published sham-controlled studies, literature reviews and meta-analyses. Trials published so far have been characterized by the use of a great variety of stimulation parameters, study designs, questionable sham controls, small sample sizes and heterogeneously depressed populations, all of which have made comparisons between studies difficult. Meta-analyses of 2-week rTMS sham-controlled studies support, for the most part, the antidepressant effects of rTMS which are statistically superior to sham. However, the degree of clinical improvement remains small, although greater efficacy has been shown with longer treatment courses and predictors of response to rTMS are progressively being identified. rTMS is a promising antidepressant treatment with overall minor adverse effects. Because the clinical efficacy of rTMS as an antidepressant remains questionable, further systematic, large-scale multicenter studies comparing rTMS to a sham and/or to an antidepressant medication along with more stringent stimulation parameters are warranted in order to identify patient populations most likely to benefit and treatment parameters most likely to optimize its antidepressant efficacy.