Repetitive transcranial magnetic stimulation for the treatment of depression Systematic review and meta - analysis

Declaration of interest The study was fundedby the Ministerio de Sanidady Consumo,Instituto de Salud Carlos III, Spain (grant no. 00/10099).T.E.S. is involved in one ofthe studies included in this reviewand is also Secretary^ Treasurerofthe International Society for Transcranial Stimulation. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique used to stimulate the human brain in vivo using very strong, pulsed magnetic fields. The technique involves the delivery of a magnetic pulse to the cortex of a subject through a hand-held stimulating coil applied directly to the head. The magnetic pulses pass unimpeded through the skull and induce an electrical current in the underlying tissue, which in turn is able to depolarise neurons (Hallet, 2000). Given its relative non-invasiveness, its potential to stimulate very focused areas of the brain and indications that it may have therapeutic effects in neuropsychiatric disorders, especially affective disorders (George et al, 1999), rTMS has been the focus of considerable research and clinical interest in recent years. Clinical interest originates mainly from about 15 placebo-controlled clinical studies involving around 200 subjects with depressive disorder or bipolar disorder in the depressed phase. It has been shown that rTMS has effects on the brain (Ji et al, 1998; Keck et al, 2000), but whether its properties are clinically useful and constitute meaningful alternatives to currently available treatments remains to be determined. Today rTMS presents an interesting and potentially promising technique but to our knowledge there has been no systematic evaluation of its efficacy using meta-analysis techniques. We undertook a systematic review of all available randomised trials and conducted a metaanalysis of relevant data to assess the efficacy of rTMS in treating depression.