Neural, Anti-inflammatory, and Clinical Effects of Transauricular Vagus Nerve Stimulation in Major Depressive Disorder: A Systematic Review.

Data on the clinical efficacy of taVNS in the treatment of MDD are limited. Although these studies showed positive results, no conclusions can be drawn regarding this topic considering the heterogeneity of these studies; as in the case of functional connectivity studies. Based on animal studies, the application of taVNS causes a decrease in the level of inflammatory factors in different parts of the brain, which also regulate the immune system. Therefore, further studies are needed to understand the effects of taVNS in patients with MDD.