A non-randomized trial of the effects of transcutaneous auricular vagus nerve stimulation on cognitive performance and resting state connectivity

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Background Transcutaneous auricular vagus nerve stimulation (taVNS) has shown promise for enhancing cognition and emotion regulation. To date, most human studies have focused on narrow learning paradigms that limit our understanding of how taVNS influences complex, integrative cognitive operations. Moreover, the underlying mechanisms of taVNS are still not well understood. Objective Building on preclinical findings that vagus nerve stimulation enhances cognitive flexibility and memory in animal models, this study investigated whether acute taVNS can modulate executive function and neural connectivity in healthy adults. Methods Using a quasi-experimental design, forty healthy participants received either active or sham taVNS while completing executive function tasks and adaptive cognitive training (BrainHQ). High-density electroencephalography (EEG) was recorded during stimulation to assess cortical activity and functional connectivity across frequency bands. Results Multivariate analyses demonstrated significant effects of taVNS on cognitive function and EEG. Post-hoc group comparisons showed that compared to sham stimulation, active taVNS was associated with improved BrainHQ performance and decreased delta-band connectivity in left frontal, central, and parietal regions. Delta-band connectivity during active taVNS was positively associated with pre-to-post improvements in mood. No difference in executive function tasks was found between active and sham taVNS. Sensitivity analyses using adjusted models showed that these effects were sensitive to age, sex, and education. Conclusion By evaluating multiple dimensions of executive function, these exploratory findings suggest that active taVNS may influence selected aspects of executive performance and frontal–parietal delta connectivity, potentially reflecting enhanced neural efficiency arising from the interaction between vagally mediated neuromodulation and continuously adaptive cognitive demands. However, these effects did not survive multiple-comparison correction and should therefore be interpreted cautiously and replicated in larger, prospectively powered studies.