the left dorsolateral prefrontal cortex to be effective in relieving symptoms of depression. Several studies have also looked at the effects of low-frequency (inhibitory) rTMS to the right prefrontal cortex, with most finding that inhibitory rTMS to the right prefrontal cortex is also efficacious in the treatment of depression (Klein et al., 1999; Januel et al., 2006; O’Reardon et al., 2007). A recent meta-analysis combined randomized trial data from 38 studies with a total of 1383 patients (Slotema et al., 2010); 28/34 studies demonstrated a benefit with rTMS, with a mean weighted effect size (mean difference / standard deviation) for all studies of 0.55 (p < 0.001). The single largest randomized placebo-controlled trial conducted to date involved the application of high-frequency (10 Hz) rTMS to the left prefrontal cortex, in daily sessions occurring five times a week for a maximum of 30 sessions over six weeks (O’Reardon et al., 2007). The authors found that active rTMS was consistently and significantly superior to sham treatment on a variety of different outcome measures.
