Effects of Transcutaneous Vagus Nerve Stimulation in Older Adults

NCT07292623 | Completed DMC

• 1 other identifier: 2025/295_I
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

Brief Summary

The autonomic nervous system consists of two branches, the sympathetic and the parasympathetic, which must work in balance. Its functioning can be measured indirectly by heart rate variability, which is the time between heartbeats, which is not constant. The more it varies, the greater the role of the parasympathetic branch, and vice versa. However, with age, an imbalance can occur and the parasympathetic branch can play a lesser role, resulting in less heart rate variability (the times between heartbeats become more similar). The aim of this study is to know if electrical stimulation in the ear can improve the balance between the two branches of the autonomic nervous system in older adults, comparing two different locations of application. The main questions to answer are: Does applying electrical stimulation to a specific area of the ear improve the balance of the autonomic nervous system? Does it also help improve hand tremors, balance, concentration, saliva production, and voice quality?

Conditions

Older Adults Without Any Specific Clinical Condition; Transcutaneous Vagus Nerve Stimulation; Autonomic Nervous System Imbalance

Keywords

Transcutaneous Electric Nerve Stimulation; Vagus Nerve; Ear Auricle; Heart Rate; Aged; Voice; Saliva; Postural Balance; Tremor; Executive Function

Outcome Measures

Primary Outcomes (1)

• HRV

  Heart Rate Variability (HRV) using Kubios app and H10 polar heart rate monitor chest strap, in periods of 5 minutes: * Frequency domain; ratio LF/HF power will be calculated along with normalised LF/HF where baseline values will set to 1; Low frequency (LF, referred to HRV frequency band 0.04-0.15 Hz); High frequency (HF = HRV frequency band 0.15-0.4 Hz); absolute powers of LF, and HF bands (ms2); normalized power (powers of LF and HF bands in normalised units, %) * Time domain: RR (mean values of RR intervals in ms) ; SDNN (Standard deviation of RR intervals); RMSSD (Root mean square of successive RR interval differences, in ms) * Non-linear methods: the poincaré plot short term variability (SD1, ms); the poincaré plot long term variability (SD2, ms). * Global measures: Stress Index (SI), square root of Baevsky's stress index; Parasympathetic nervous system (PNS) index

  Change from pre-tVNS (baseline= post initial battery of tests, about minute 35 after initiating the session) and during tVNS (post second battery of tests, 5 minutes before the end of the session, about minute 70)

Secondary Outcomes (8)

• HRV

  Change from pre-tVNS (baseline = post initial battery of tests, about minute 35 after initiating the session) and initial tVNS (5 minutes after setting the intensity of tVNS, about 45 minutes after initiating the session)

• Hand tremor

  Change from pre-tVNS (baseline= initial battery of tests, about minute 10 to 15 after initiating the session) and during tVNS (post = second battery of tests, about 50 to 55 minutes after after setting the intensity of tVNS)

• Salive

  Change from pre-tVNS (baseline= initial battery of tests, from minute 15 to 20 after initiating the session) and during tVNS (post second battery of tests, about 55 to 60 minutes after after setting the intensity of tVNS)

• Flanker test

  Change from pre-tVNS (baseline= initial battery of tests, about 20 minutes after initiating the session) and during tVNS (post second battery of tests = 60 minutes after initiating the session)

• Balance test

  Change from pre-tVNS (baseline= post initial battery of tests, from minute 25) and during tVNS (post second battery of tests = from minute 65)

Other Outcomes (2)

• Efficacy of sham intervention

  Immediately after the intervention

• Amplitude of electrical stimulation

  When initiating tVNS or sham-located tVNS, that means, 40 minutes after the initiation of the session

Study Arms (2)

Active tVNS

ACTIVE COMPARATOR

While acclimatization of the participant (10 minutes) the different tests will be explained, the chest strap will be placed, its synchronization with the HRV measurement system will be checked, and the TENS equipment will be placed on the waist using a fanny pack. The pre-stimulation assessment will be carried out (from 10 to 40 minutes after initiating the session). Participants will be allowed to try each one to familiarize themselves with it. All the tests will be performed (tremor, saliva, Flanker, balance, voice, Heart Rate Variability- HRV). At the end of this first part, the stimulation will be applied at the left ear in the area innervated by the vagus nerve (concha and cymba concha),and all the variables will be measured again in the same order during the actual electrical stimulation, after a new HRV measurement (from 45 to 75´). Then, the last HRV measurement will be taken and the participant will be asked about tolerance, the occurrence of adverse effects, and blinding.

Device: Active location tVNS

Sham tVNS

SHAM COMPARATOR

At the beginning, the different tests will be explained, the chest strap will be placed, its synchronization with the HRV measurement system will be checked, and the TENS equipment will be placed on the waist using a fanny pack. Next, the pre-stimulation assessment will be carried out. Participants will be allowed to try each one to familiarize themselves with it. All the tests will be performed (tremor, saliva, Flanker, balance, voice, Heart Rate Variability- HRV). At the end of this first part, the stimulation will be applied at the left ear in the area not innervated by the vagus nerve (scapha) and all the variables will be measured in the same order during the sham electrical stimulation, after a new HRV measurement. Then, the last HRV measurement will be taken and the participant will be asked about tolerance, the occurrence of adverse effects, and blinding.

Device: Sham Comparator

Interventions

Active location tVNS DEVICE

The tVNS will be performed at 20 Hz and 200 microseconds, in the area innervated by the auricular branch of the vagus nerve (cymba concha and concha) in the active location. The intensity will be set above the sensory threshold (intense tingling sensation) but below the level of discomfort. The TENS will be set to 27 seconds of working time, with a 3-second ramp-up and 90 seconds off. It will last until the end of the last HRV test.

Also known as: tVNS, aVNS, auricular vagus nerve stimulation, Active tVNS

Active tVNS

Sham Comparator DEVICE

The tVNS will be performed at 20 Hz and 200 microseconds, in the area not innervated by by the auricular branch of the vagus nerve (scapha) for sham TENS. The intensity will be set above the sensory threshold (intense tingling sensation) but below the level of discomfort. The TENS will be set to 27 seconds of working time, with a 3-second ramp-up and 90 seconds off. It will last until the end of the last HRV test.

Also known as: Sham tVNS, sham aVNS, Sham auricular vagus nerve stimulation

Sham tVNS

Eligibility Criteria

• Age: 65 Years - 80 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Older Adult (65+)

You may qualify if:

• Non-smokers aged 65 to 80, with BMI from 18.5 to less than 30, who consider themselves healthy and are able to maintain their balance for at least 1 minute without assistance, living in A Coruña (Spain), with a 50% allocation to each sex

You may not qualify if:

• systolic blood pressure above 160 mm Hg and diastolic blood pressure above 100 mm Hg,
• previous vagotomy, history of syncope in the last two years, or lack of reliable reading in heart rate variability
• presence of chronic pain (migraine, back, neck, shoulder, etc.) or being diagnosed with or receiving treatment for malignant, cardiovascular disease (excluding hyperlipidaemia and hypercholesterolaemia), respiratory, neurological or autonomic, metabolic (e.g. diabetes), osteoarticular of autoimmune origin (e.g. arthritis), psychiatric or history of treatment with antidepressants or anxiolytics
• impaired cognitive level
• presence of any contraindication or difficulty in applying TENS: pacemaker, defibrillator or any implanted electronic device, apprehension of electric current, burns or irritated skin or allergic reaction or any alteration in the area that prevents the electrode from being placed on the left ear;
• previous application of electrical stimulation to the ear

Sponsors & Collaborators

• Universidade da Coruña: lead

Study Sites (1)

Faculty of Physiotherapy

A Coruña, La Coruña, 15006, Spain

Location

MeSH Terms

Conditions

Tremor

Condition Hierarchy (Ancestors)

Dyskinesias; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Officials

• Alicia Martínez-Rodríguez, Lecturer

  Universidade da Coruña (University of A Coruna)

  PRINCIPAL INVESTIGATOR

• Olalla Bello, Lecturer

  Universidade da Coruña (University of A Coruna)

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Masking Details: The volunteers will be randomized by sex to begin with one of two electrode locations: cymba concha and cavum concha at the left ear (active session); or scapha and lobule at the left ear (sham-session). These two interventions will be denominated as Transcutaneous Vagus Electrical Nerve Stimulation (t-VNS) and Sham Transcutaneous Vagus Electrical Nerve Stimulation (sham t-VNS). Allocation concealment, stratified by sex, will be ensured as the person will choose a piece of paper with the assignment coded with numbers (real/placebo) from a bag containing all the coded options that only the person applying the stimulation will see and understand (coded). The researcher analysing the results does not know whether condition 1 or 2 corresponds to the placebo or active location.
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Lecturer; Faculty of Physical Therapy. Researcher; Psychosocial Intervention and Functional Rehabilitation Group

Model Details: All participants will undergo both conditions, placebo and real location, in a randomly assigned order. Placebo stimulation will be performed in a different location, using the same electrical parameters. The second session will be performed in the same way, but using the application not used in the previous session (placebo or active, as appropriate). Each session will follow this order: 10 minutes (min) of acclimatization, connection of equipment and checking that the chest band is working; 10 to 35 min performance of the first set of tests; from 35 to 40 min measurement of heart rate variability (HRV); 40-45 min, searching for the highest intensity tolerated without discomfort- initiation of transcutaneous vagus nerve stimulation (sham or active tVNS); 45-50 min, HRV; from 50 to 75´ new performance of the set of tests with tVNS; 75-80 min final HRV; 80 min- tolerance, adverse effects (and 48 h after), blinding

Study Record Dates

• First Submitted: November 29, 2025
• First Posted: December 18, 2025
• Study Start: December 19, 2025
• Primary Completion: February 10, 2026
• Study Completion: February 12, 2026
• Last Updated: March 2, 2026

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will share
• Shared Documents: SAP, CSR
• Time Frame: Beginning 1 year after publication and with no ending while Zenodo will keep the data
• Access Criteria: The results will be included in a document which will be shared by Zenodo to all the investigators interested in them by direct access.

Locations

ES (1)