In a recent publication in the International Journal of Neuropsychopharmacology, researchers sought to assess the clinical evidence and the neural and anti-inflammatory effects of transauricular vagus nerve stimulation (taVNS) in managing MDD.

The authors wrote, “The discovery of effective treatments for major depressive disorder (MDD) may help target different brain pathways. Invasive vagus nerve stimulation (VNS) is an effective neuromodulation technique for the treatment of MDD; however, the effectiveness of the noninvasive technique, transauricular VNS (taVNS), remains unknown.”

For this systematic review, the authors reviewed the clinical efficacy and neural connectivity of taVNS in MDD in humans. They assessed the alterations in inflammatory markers after using taVNS in humans or animal models of depression. The researchers also conducted a risk of bias assessment in all human studies.

A total of five studies assessed the influences of taVNS in patients with depression. The authors noted that although the studies demonstrated the efficacy of taVNS in treating depression, the studies employed heterogeneous methodologies and had limited data, preventing the conduct of pooled quantitative analyses. They also noted that analysis could not be performed for studies that explored the modulation of connectivity between brain areas; of the six publications, five were centered on the same experiment, and the animal studies that examined the existence of inflammatory markers disclosed a decrease in the level of proinflammatory cytokines or receptor expression.

Based on their findings, the authors concluded that data from randomized, controlled trials and neurophysiological data on the efficacy of taVNS in the treatment of MDD are limited. They added that while the available studies presented positive results, no conclusions can be made because of the heterogeneity of these studies, as in the case with functional connectivity studies.

Finally, the authors wrote, “The results of current studies investigating the clinical efficacy and neuroendocrine mechanisms underscoring the taVNS effects remain inconclusive. Hence, future sham-controlled randomized trials, including the assessment of neurophysiological data, are necessary to validate our findings.”

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.