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Kathryn R. Cullen. 1 Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota.
Suzanne Jasberg. 1 Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota.
Brent Nelson. 1 Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota.
Bonnie Klimes-Dougan. 1 Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota.
Kelvin O. Lim. 1 Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota.
Paul E. Croarkin. 2 Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota.
Funding: This study was supported by the MnDRIVE Neuromodulation Innovation Grant. The study was also supported, in part, by Brainsway, who provided the use of the deep TMS machine at no charge.
Address correspondence to: Kathryn R. Cullen, MD, Department of Psychiatry, University of Minnesota, F256/2B West Building, 2450 Riverside Avenue, Minneapolis, MN 55454, E-mail: [email protected]
Introduction
Major depressive disorder frequently emerges during adolescence and can be difficult to treat. Only 50%-60% of adolescents respond to conventional treatments (e.g., antidepressant medication and cognitive behavioral therapy) after 12 weeks (March et al. 2006; Brent et al. 2008). Expert reviews of longer term follow-up studies suggested that 40% of adolescents with depression do not achieve remission with treatment and can therefore be said to have "treatment-resistant depression" (TRD) (Maalouf et al. 2011). Since these adolescents with TRD are at risk for persistent depression in adulthood, morbidity, and suicide, there is an urgent need to develop novel interventions to relieve depression in adolescents with TRD (Maalouf et al. 2011).
Transcranial magnetic stimulation (TMS) is a procedure in which a magnetic coil that generates a pulsatile magnetic field from a rapidly oscillating electrical current is placed on the scalp, to induce electrical currents in the brain (Roth et al. 2007). TMS is used in neuroscientific research to investigate brain functioning, and when used repetitively over the dorsolateral prefrontal cortex (a brain region that is hypoactive in depression) (Mayberg 1997), has been shown to alleviate depression symptoms (Kedzior and Reitz 2014). In 2008, the U.S. Food and Drug Administration (US FDA) approved the use of repetitive TMS with the Neurostar TMS system, which uses a figure-8 coil, with a protocol that included specified settings regarding intensity, frequency, and number of pulses. Recent advances in custom coil technology led to the development of H coils that support stimulation of deeper,...