Impact of Transcutaneous Vagal Nerve Stimulation on Stress Response in Major Depression

This study will identify the sex-dependent impact of expiratory-gated transcutaneous vagus nerve stimulation (tVNS) on the modulation of the stress response circuitry and associated physiology in major depressive disorder (MDD). We will evaluate a sample of 80 adults with recurrent MDD randomized to receive active or sham expiratory-gated tVNS during a functional magnetic resonance imaging (fMRI) session, with simultaneous mood and physiological assessments. We hypothesize that expiratory-gated tVNS will effectively modulate, in a sex-dependent manner, specific brainstem-cortical pathways of the stress circuitry and attenuate physiological deficits in MDD.