The study will be up to 14 visits, which will occur for up to a 1 year period. The first visit is a screening visit, which will take about one hour to determine eligibility. If participants are eligible, participants will be scheduled for a baseline visit and 12 monthly visits to determine the antidepressant effects and possible side effects.
The purpose of this study is to 1) explore whether vagal nerve stimulation (nVNS) using a hand- held non-invasive device (gammaCore™) works to treat depression and 2) to confirm gammaCore™'s safety profile.