Effects of Left Versus Right Dorsolateral Prefrontal Cortex Repetitive Transcranial Magnetic Stimulation on Affective Flexibility in Healthy Women: A Pilot Study.

Abstract

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.