Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) Attenuates Early Increases in Heart Rate Associated with the Cold Pressor Test

Abstract Introduction: Transcutaneous auricular vagus nerve stimulation (taVNS) may be useful in the treatment of disorders characterized by low vagal tone. Acute taVNS decreases resting heart rate in healthy individuals, but little is known regarding the effects of taVNS on heart rate during a stress response. The cold pressor test (CPT) is a validated stress induction technique that reliably elicits a sympathetic stress response with marked increases in heart rate, anxiety, stress, and pain. We investigated the acute effects of taVNS on the stress response induced by the CPT. Methods: 24 healthy adults (10 female, mean age = 29) were recruited to participate in this randomized, double blind, crossover pilot trial. Subjects received active taVNS concurrent with a CPT followed by sham stimulation concurrent with a second CPT (duration of each round of taVNS/CPT was 2 minutes). Order of stimulation condition (active versus sham) was randomized. Heart rate, along with subjective ratings of anxiety, stress, and pain, were collected before, during, and after each round of concurrent stimulation and CPT. Results: In both stimulation conditions, heart rate was significantly elevated from baseline in response to the CPT (n=21). Results revealed a reduced heart rate increase in the active taVNS group, relative to the sham group, during the first 40 seconds of the CPT (delta HR = 12.75 ± 7.85 in active condition and delta HR = 16.09 ± 11.43 in the sham condition, p<0.05). There were no significant differences in subjective ratings between the active taVNS and sham stimulation conditions. Conclusion: In this double blind, sham-controlled, crossover study, taVNS significantly blocked increases in heart rate during the early portion of the CPT. Future studies are needed to investigate the effects of various taVNS doses and parameters on the CPT and other forms of stress induction. Research Category and Technology and Methods Basic Research: 12. Vagus Nerve Stimulation (VNS) Keywords: taVNS, VNS, Stress, Anxiety