Transcranial Magnetic Stimulation (TMS) involves placing electrodes on people's heads and passing brief but strong magnetic pulses through their brain. Canada and Israel already use this technology to treat people with major depression and in the U.S. the Food and Drug Administration has recently approved this treatment. The pulses can be fast- or slow-frequency and it has been suggested that slow-frequency pulses may be safer and have fewer side effects. D.J.L.G. Schutter from Utrecht University in the Netherlands reviewed 9 studies into this topic involving 252 participants. He found that slow frequency TMS had a beneficial effect on people and could be just as effective as fast-frequency TMS.
Schutter, D.J.L.G. - Quantiative review of the efficacy of slow-frequency magnetic brain stimulation in major depressive disorder Psychological Medicine November 2010, 40(11), 1789-1795