Less stress? Effects of taVNS on physiological parameters and cognitive performance during a mental stressor.

BACKGROUND
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.
METHODS
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.
RESULTS
taVNS 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.
CONCLUSION
taVNS 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.