The Effects of Transcutaneous Auricular Vagal Nerve Stimulation on Cognition in Healthy Individuals: A Meta-Analysis

Objective: Transcutaneous auricular vagal nerve stimulation (taVNS) may benefit cognition in healthy adults but may differentially affect specific domains of cognitive function. Currently, optimal stimulation parameters of taVNS have yet to be identified and the overall effectiveness of this approach remains unclear. Method: A literature review and random effects meta-analysis evaluated the effects of taVNS on cognitive performance outcomes across domains of function and outcome metrics (accuracy and response times). Subgroup meta-analyses and meta-regression models explored the moderating effects of stimulation parameters on performance outcomes. Results: Meta-analyses on 19 eligible studies indicated a weighted effect size of 0.21 for the effect of taVNS on overall cognitive performance, with significant effects on measures of executive function and measures of accuracy. Parameter meta-analyses indicated that stimulation site was most associated with improvements in executive function (gtragus = 2.39, gcymba concha = 0.48; Q = 39.84, p < .0001; β = −2.33, p = .03). Conclusions: taVNS may improve cognition, particularly executive function, and stimulation parameters may differentially influence outcomes. Continued research into the effects of taVNS as well as optimal stimulation parameters will be beneficial. Key Points Question: The present study assessed the effectiveness of transcutaneous auricular vagal nerve stimulation (taVNS) on healthy cognition using meta-analytic techniques. Findings: This analysis finds that taVNS has a beneficial impact on cognition, particularly executive functions. Importance: This is the first quantitative assessment of the effects of taVNS and may be valuable to those using taVNS to improve cognitive function. Next Steps: This review highlights future directions for cognitive research using taVNS, particularly in further assessment of optimal stimulation parameters.