Quantitative review of the efficacy of slow-frequency magnetic brain stimulation in major depressive disorder

Background. Slow-frequency repetitive transcranial magnetic stimulation (rTMS) to the frontal cortex has been suggested as a safer and better tolerable alternative to fast-frequency rTMS in the treatment of major depressive disorder (MDD). The aim of the present study was to examine the efficacy of slow-frequency rTMS to the frontal cortex in MDD. Method. A literature search was carried out in the databases PubMed and Web of Science in the period between January 1994 and July 2009 with the search terms 'depression' and 'transcranial magnetic stimulation'. Nine double-blind sham-controlled parallel intention-to-treat studies (252 patients) fulfilled inclusion criteria and were entered in a random-effects meta-analysis. Results. The test for heterogeneity was not significant (Q(T)=9.63, p=0.38). An overall weighted moderate mean effect size (d=0.63, 95% confidence interval=0.03-1.24) for active treatment was observed. Conclusions. The findings suggest that slow-frequency rTMS to the frontal cortex is more effective than sham treatment and may be equally effective as fast-frequency rTMS in the treatment of MDD.