Efficacy of vagus nerve stimulation in the treatment of depression.

Major depressive disorder is a disease with prominent individual, medical and economic impacts. A relevant proportion of depressive patients suffering from a therapy-resistant course are increasingly being treated with antidepressant brain stimulation techniques. One of these interventions is the vagus nerve stimulation that has recently been tested in a number of clinical trials. To date, the acute and long-term efficacy of vagus nerve stimulation are still under debate. Thus further studies are required, especially since the exact mode of action of vagus nerve stimulation is still not well understood. In this paper we will review the results of existing clinical trials as well as the neurobiological effects measured with neuroimaging, biochemical and electrophysiology approaches.