Fitzgerald PB et al. (2006) A randomized trial of low-frequency right-prefrontal-cortex transcranial magnetic stimulation as augmentation in treatment-resistant major depression. Int J Neuropsychopharmacol 9: 655–666

Several small studies have indicated that low-frequency right prefrontal repetitive transcranial magnetic stimulation (rTMS) might have antidepressant properties; however, the effectiveness of this treatment in clinical practice has not been evaluated and the optimum treatment parameters are not well characterized.

In a two-arm double-blind trial, 130 patients with treatment-resistant depression were sequentially randomized to either 1 Hz or 2 Hz rTMS over the right prefrontal cortex. Patients received 10 rTMS sessions over a 2-week period. Following the tenth session, patients classified as 'initial responders' were offered a 2-week extension of treatment, while nonresponders were randomized to left prefrontal cortex rTMS at a frequency of either 5 Hz or 10 Hz.

Following 2 weeks of right-sided rTMS, 29% of patients met the response criteria (>50% reduction in the 17-item Hamilton Depression Rating Scale); 47% of patients met these criteria by week 4. Despite receiving double the 'dose', on the basis of pulse number the response rate in patients receiving 2 Hz stimulation was no higher than in those receiving 1 Hz. Notably, of the 30 patients who failed to respond to right-sided rTMS and crossed over to receive high-frequency left-sided rTMS, five met the response criteria following 4 weeks of treatment. By study completion, 51% of the entire study population had achieved the response criteria and 27% the remission criteria. In general, rTMS was acceptable to patients, as indicated by the low dropout rate. The authors conclude that low-frequency right-sided rTMS seems to be a clinically useful therapy for patients with treatment-resistant depression.