# Effects of taVNS on physiological responses and cognitive performance during a mental stressor

## TL;DR

This study investigated whether taVNS could reduce stress and improve cognitive performance during a mentally demanding task, but found no significant effects on stress or performance.

## Contribution

The study is one of the first to explore taVNS effects on acute mental stress and cognitive performance in a socially evaluated context.

## Key findings

- taVNS did not reduce self-reported stress or anxiety during a mental stressor.
- taVNS had no effect on cognitive performance during the PASAT task.
- taVNS increased heart rate variability and electrodermal activity during stimulation.

## Abstract

Transcutaneous auricular vagus nerve stimulation (taVNS) affects autonomic function and enhances cognitive performance by increasing vagal activation and central noradrenergic activity. Nevertheless, the impact of taVNS on acute mental stress remains largely unexplored. This study examined whether taVNS can mitigate the acute sympathetic stress response and improve cognitive performance during a socially evaluated version of the Paced Auditory Serial Addition Task (PASAT). The PASAT is a demanding task that assesses working memory and divided attention and serves as a potent stressor. Forty-one young healthy volunteers were randomly assigned to receive either taVNS stimulation (n = 21) at the left cymba conchae or a sham stimulation (n = 20) at the ear lobe. Participants received 15-min stimulation before they were challenged with the PASAT while the stimulation continued. Electrocardiogram, electrodermal activity and self-reports of stress and anxiety were collected. Transcutaneous auricular vagus nerve stimulation increased heart rate variability and sympathetic electrodermal activity during the stimulation. Self-reports, cognitive performance and physiological stress responses remained unaffected by taVNS. Physiological measures were highly intercorrelated in participants receiving taVNS. Transcutaneous auricular vagus nerve stimulation did not influence physiological, psychological or behavioral responses to an acute mental/social stressor. The strong intercorrelation between sympathetic and parasympathetic indexes in the taVNS group, however, suggests that taVNS improves autonomic regulation in healthy participants.