Research Paper Volume 11, Issue 14 pp 4836—4857

Effects of transcutaneous vagus nerve stimulation in individuals aged 55 years or above: potential benefits of daily stimulation

Beatrice Bretherton 1, , Lucy Atkinson 1, , Aaron Murray 1, , Jennifer Clancy 2, , Susan Deuchars 1, , Jim Deuchars 1, ,

  • 1 School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
  • 2 School of Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK

received: May 9, 2019 ; accepted: June 28, 2019 ; published: July 30, 2019 ;

https://doi.org/10.18632/aging.102074
How to Cite

Copyright © 2019 Bretherton et al. This is an open-access article distributed under the terms of the Creative Commons Attribution (CC BY) 3.0 License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Ageing is associated with attenuated autonomic function. Transcutaneous vagal nerve stimulation (tVNS) improved autonomic function in healthy young participants. We therefore investigated the effects of a single session of tVNS (studies 1 and 2) and tVNS administered daily for two weeks (study 3) in volunteers aged ≥ 55 years. tVNS was performed using modified surface electrodes on the tragus and connected to a transcutaneous electrical nerve stimulation (TENS) machine. Study 1: participants (n=14) received a single session of tVNS and sham. Study 2: all participants (n=51) underwent a single session of tVNS. Study 3: participants (n=29) received daily tVNS for two weeks. Heart rate variability and baroreflex sensitivity were derived. Quality of life (QoL), mood and sleep were assessed in study 3. tVNS promoted increases in measures of vagal tone and was associated with greater increases in baroreflex sensitivity than sham. Two weeks of daily tVNS improved measures of autonomic function, and some aspects of QoL, mood and sleep. Importantly, findings showed that improvements in measures of autonomic balance were more pronounced in participants with greater baseline sympathetic prevalence. This suggests it may be possible to identify individuals who are likely to encounter significant benefits from tVNS.

Abbreviations

ABVN: auricular branch of the vagus nerve; BMI: body mass index; BP: blood pressure; BRS: baroreflex sensitivity; ECG: electrocardiogram; HF: high frequency power; HR: heart rate; HRT: hormone replacement therapy; HRV: heart rate variability; LF: low frequency power; LF/HF: ratio of low frequency to high frequency power; LL-TS: low-level tragus stimulation; nSD1: SD1 normalised relative to heart rate; nSD2: SD2 normalised relative to heart rate; nuHF: normalised high frequency power; nuLF: normalised low frequency power; PAF: paroxysmal atrial fibrillation; POMS: profile of mood states; pRR50: percentage of number of pairs of adjacent RR intervals differing by more than 50 ms; QoL: quality of life; RR interval: interval between adjacent R peaks; RMSSD: square root of the squared of differences between adjacent RR intervals; S: area of the ellipse of the Poincaré plot; SBP: systolic blood pressure; SD1: standard deviation of points perpendicular to the axis of line-of-identity; SD2: standard deviation of points along the axis of line-of-identity; SD2/SD1: ratio of SD2 to SD1; SDRR: standard deviation of all RR intervals; SEM: standard error of the mean; SF-36: questionnaire providing a measure of health-related quality of life; TENS: transcutaneous electrical nerve stimulation; tVNS: transcutaneous vagal nerve stimulation; VNS: vagal nerve stimulation.