The project will use TNS in under open-label conditions, using the same stimulation parameters as have been used in prior studies in MDD by itself and in treatment-refractory epilepsy. Subjects will be seen every two weeks during the 8 week study. At the end of the 8 weeks, the TNS systems will be returned and the adjunctive treatment will end. The co-primary endpoints are the changes in depression severity and in PTSD severity from enrollment to the week 8 visit.