Acute Effect of Transcutaneous Auricular Vagus Nerve Stimulation in Two Different Locations on Blood Pressure and Cardiac Autonomic Modulation in Healthy and Hypertensive Individuals: Pilot Study of a Randomized Crossover Clinical Trial.

Small sample: 14 per group, single-center recruitment from a university waiting list and social media. No sham control group, so the small changes seen cannot be attributed specifically to vagal nerve activation rather than to non-specific sensory stimulation or expectation. The hypertensive group was on average 14 years older than the healthy group (45 vs 31 years), which the authors acknowledge as a potential confound for both blood pressure and autonomic outcomes. Only acute effects were measured (during and 10 minutes after a single 30-minute session); no long-term or repeated-session data. Stimulation intensity was individually adjusted to sensory threshold but not systematically recorded by group or site, preventing subgroup-specific intensity analyses.

The authors declare no conflicts of interest. The work was funded by CAPES (Coordination for the Improvement of Higher Education Personnel), a Brazilian government body that supports higher education research.

Do not read the small blood pressure changes as evidence that ear stimulation treats hypertension. In the hypertensive group, cymba conchae stimulation left blood pressure completely unchanged, and the only significant change was a small post-stimulation diastolic reduction with tragus. There was no sham control, so even the modest changes seen in the healthy group cannot be attributed to vagal activation specifically. The hypertensive group was also 14 years older on average, which independently affects blood pressure and autonomic function.