To determine the antidepressant mechanism of action for repetitive transcranial magnetic stimulation (rTMS) to the left dorsolateral prefrontal cortex (DLPFC) in healthy women. Our primary hypothesis was that a single session of left DLPFC rTMS, compared with a session of right DLPFC rTMS, would result in better (reduced) negative nonaffective switch costs in healthy women.
The antidepressant mechanism of action for rTMS is not clear. It is possible that rTMS to the DLPFC improves emotion regulation, which could be a part of its antidepressant mechanism.
Twenty-five healthy women were randomized to receive left high-frequency (HF) rTMS versus right HF rTMS in one session and then contralateral stimulation during a second session. Emotion regulation was assessed via switch costs for reappraisal of negatively valenced information on an affective flexibility task.
For negative nonaffective switch costs, the interaction effect in the two-way ANOVA was not significant (F1,19=3.053, P=0.097). Given that left HF rTMS is the approved treatment for depression, post hoc t tests were completed with particular interest in the left-side findings. These tests confirmed that negative nonaffective switch costs significantly improved immediately after left rTMS (t1,19=2.664, P=0.015) but not right rTMS.
These findings suggest that left DLPFC HF rTMS may lead to antidepressant effects by improving the regulation of emotion.
Departments of *Psychiatry and Surgery
∥Psychiatry, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
†Kaiser Southern California Permanente Medical Group, Los Angeles, California
‡Private Practice, Carmel, New York
§Department of Psychology, Miami University, Oxford, Ohio
¶Department of Psychiatry, Weill Cornell Medicine, New York, New York
#Executive Division, National Center for Posttraumatic Stress Disorder, White River Junction, Vermont
Present address: Crystal Lantrip, PhD, VISN 17 Center of Excellence for Research in Returning War Veterans, Central Texas Veterans Health Administration, Waco, Texas 76711.
Portions of this work were presented at the Annual Meeting of the Society of Biological Psychiatry, May 2017, San Diego, California.
Supported in part by the Department of Psychiatry, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire.
The authors declare no conflicts of interest.
Correspondence: Crystal Lantrip, PhD, VA VISN 17 Center of Excellence for Research in Returning War Veterans, Central Texas Veterans Health Administration, 4800 Memorial Drive (151C), Waco, Texas 76711 (email: firstname.lastname@example.org).
Received January 12, 2018
Accepted January 24, 2019