Analysis of taVNS effects on baroreflex sensitivity and autonomic nervous system regulation during head-up tilt test

Baroreflex dysfunction and autonomic imbalance are key pathophysiological features of hypertension, but current pharmacological approaches often fail to address these neural mechanisms. This study investigated whether transcutaneous auricular vagus nerve stimulation (taVNS) affects autonomic regulation during blood pressure perturbation. In a randomized, single-blind, sham-controlled, crossover design experiment, 32 normotensive adults received 90-min taVNS or sham exposure. Blood pressure perturbation was induced with the head-up tilt test (supine–tilt–supine). Baroreflex sensitivity (BRS) was analyzed only during the 10-minute tilt phase, whereas heart rate variability (HRV) was analyzed across four 5-minute segments (S-baseline, early-tilt, late-tilt, recovery). In the direct crossover analysis of the primary BRS outcome, pre-to-post changes did not differ significantly between taVNS and sham, and the baseline-adjusted sensitivity analysis yielded the same conclusion. Among the secondary HRV outcomes, differences averaged across analysis segments were significant only for SDNN and pNN30, whereas no analysis-segment-specific interaction was significant. Descriptive within-visit comparisons showed increases in BRS and several HRV measures during the taVNS visit. These findings provide preliminary evidence compatible with cardiovagal modulation during orthostatic stress, but do not establish a taVNS-specific improvement in BRS or blood pressure regulation. Further research involving patient cohorts and longitudinal study protocols is needed.