Past, present and future of transcranial magnetic stimulation (TMS) in the treatment of psychiatric disorders

Transcranial magnetic stimulation (TMS) is a brain stimulation technique used for the treatment of major depression and other psychiatric disorders. Initially used as a research tool in neurophysiology, TMS has been subsequently extended to the therapeutic area of depressive disorders and approved in many countries for this purpose. TMS uses magnetic fields to deliver electricity into specific areas of the cerebral cortex, mainly the dorso-lateral prefrontal cortex. Several randomized clinical trials (RCTs) conducted with TMS over the last decade have allowed its approval by the FDA for the treatment of major depressive episodes with poor response to standard antidepressants. In addition, meta-analyses and international treatment guidelines have more recently defined stimulation parameters and safety standards. Future directions in the field should further explore the clinical efficacy and safety of specific forms of TMS like deep TMS and theta burst stimulation, which allow to reach deeper anatomic targets and to shorten the overall duration of stimulation. The utility of maintenance session and the interaction with specific psychotropic compounds represent areas that need to be further investigated as well. To date, TMS is likely the non-invasive brain stimulation intervention with the strongest evidence in terms of efficacy in psychiatric disorders, as documented by RCTs and meta-analyses. Nonetheless, the efficacy of TMS needs to be further investigated in other psychiatric disorders with preliminary, encouraging results in different fields. The tolerability and safety profile of TMS are advantageous, the technique being non-invasive, generally well-accepted and devoid of systemic side-effects.