Skip to content

Mechanisms of Transcutaneous Auricular Vagus Nerve Stimulation in Depression

Physiological and Molecular Mechanisms of Transcutaneous Auricular Vagus Nerve Stimulation in Depression

Status
Recruiting
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07022171
Acronym
AddVNS
Enrollment
86
Registered
2025-06-15
Start date
2025-03-18
Completion date
2030-03-17
Last updated
2025-06-15

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Depressive Disorder, Bipolar Disorder

Keywords

transcutaneous, auricular, vagus nerve stimulation, biomarkers, depression

Brief summary

Invasive vagus nerve stimulation (VNS) is an approved treatment of treatment-resistant depression (TRD) in Europe and in USA. Because of the associated possible surgical complications as well as side effects, invasive VNS is applied limitedly in the treatment of depression. Transcutaneous auricular VNS (tVNS), on the other hand, is a non-invasive alternative to traditional invasive VNS. tVNS is still considered an experimental treatment for depression. This is due to the limited high-quality evidence from randomized clinical studies, the not yet fully understood biological mechanisms of action, along with overall limited knowledge about the optimal stimulation parameters. To address these issues, the AddVNS study was initiated. The AddVNS study intends to recruit n=86 patients of the Max Planck Institute of Psychiatry with depression. The patients participating in the AddVNS study are going to receive either tVNS or sham tVNS for a period of 6 weeks. The primary objective of the study is to identify biological, psychological, socio-economic, and clinical biomarkers associated with treatment progression and response to treatment in patients with depression undergoing tVNS. To achieve this, an exploratory design with an assessment of many different parameters including psychophysiology, imaging, blood-based multi-omics, microbiome, psychometrics and neuropsychology will be used.

Detailed description

Background: Depression is one of the most prevalent mental disorders worldwide and is associated with the highest burden of disease among all psychiatric disorders. Invasive vagus nerve stimulation (VNS) has been approved for the treatment of treatment-resistant depression (TRD). However, invasive VNS is applied limitedly in the treatment of depression due to the associated possible surgical complications and side effects. Transcutaneous auricular VNS (tVNS), on the other hand, is a non-invasive alternative to invasive VNS. During the last decade, the effects of tVNS have been examined in an increasing number of clinical trials across many different disorders, with depression being one of the most prominent areas of interest. Nevertheless, tVNS is still considered an experimental treatment for depression. Reasons for this categorization come from the limited high-quality evidence from randomized clinical studies, the not yet fully understood biological mechanisms of action, along with overall limited knowledge about the optimal stimulation parameters. To address these issues, we initiated the AddVNS study. The primary objective of the study is to identify biomarkers of tVNS and to better understand its biological mechanisms of action in the treatment of depression. Material and methods: The AddVNS is a monocentric, exploratory-prospective, randomized, double-blind, sham-controlled interventional study that recruits adult and legally competent patients with current MDD or bipolar disorder with current depression who are treated in MPIP (either inpatient or day clinic treatment). The participants are going to receive either tVNS or sham tVNS for a period of 6 weeks. Both tVNS and sham tVNS will be carried out as an adjuvant, i.e. in addition to the regular treatment of the participants. The intervention will take place three times a day from Monday to Friday. Each of the three daily sessions is going to last 30-60 minutes, depending on patient tolerance. The procedures for sham tVNS will be identical to tVNS, with the only exception that the sham tVNS will be performed with no current output. Participants and investigators are blinded to the assignment of participants to a study arm, except for the investigators responsible for the stimulation. The AddVNS study includes a wide range of assessments, which will be identical for both study arms. Psychophysiological measurements (pupillometry, respiratory rate, 3-channel ECG, skin conductance level, photoplethysmography and an electrogastrogram) will be conducted at baseline, after 3 weeks of intervention and at the end of the 6-week intervention (for a small number of patients, two additional psychophysiological measurements are planed). Actigraphy will take place throughout the 6-week intervention. Two MRI scans are planned over the course of the AddVNS study; one scan is scheduled at baseline and one after the 6-week intervention. Participants will have a total of three venous blood samples taken over the course of the 6-week intervention. They will be asked to collect stool samples that will be used for microbiome analysis at baseline, after 3 weeks of intervention and at the end of the 6-week intervention. Participants will be also asked to fill out self-rating questionnaires (patient health questionnaire 9 and 15, Beck Depression Inventory II, Snaith-Hamilton-Pleasure-Scale, Questionnaire for complaints of cognitive disturbances) once a week, while two further questionnaires will be obtained at baseline and after the 6-week intervention (Rejection Sensitivity Questionnaire, World Health Organization Disability Assessment Schedule questionnaire). During a clinical interview at baseline, after 3 weeks of intervention and after 6 weeks of intervention, clinician-rating scales (Montgomery-Åsberg Depression Rating Scale, Hamilton Rating Scale for Depression with 21 items, Hamilton Rating Scale for Anxiety, Global Assessment of Functioning) will be obtained. Furthermore, a neuropsychological assessment is carried out at baseline and after the 6-week intervention, while a personality assessment will be performed at baseline. To assess the longitudinal effects of tVNS, we will ask the patients to fill out self-rating questionnaires (patient health questionnaire 9 and 15, Beck Depression Inventory II, Snaith-Hamilton-Pleasure-Scale, Questionnaire for complaints of cognitive disturbances, Rejection Sensitivity Questionnaire, World Health Organization Disability Assessment Schedule questionnaire) 6 and 12 weeks after the end of the intervention. Discussion: Taken together, the main goal of the AddVNS study is to identify biological, psychological, socio-economic, and clinical biomarkers associated with treatment progression and response to treatment in patients with depression undergoing tVNS. The strength of the study lies in its study design, as AddVNS is a randomized controlled trial combining a meticulous documentation of the tVNS procedure with a wide assessment of many different parameters. This makes the AddVNS study one of the most extensive studies of tVNS in depression to date.

Interventions

DEVICEtranscutaneous auricular vagus nerve stimulation

Half of the patients are randomized to the arm receiving transcutaneous auricular vagus nerve stimulation for a period of six weeks. Transcutaneous auricular vagus nerve stimulation will be carried out as an adjuvant, i.e. in addition to the regular treatment of the participants. The intervention will take place three times a day from Monday to Friday. Each of the three daily sessions is going to last 30-60 minutes, depending on patient tolerance.

Half of the patients are randomized to the arm receiving sham transcutaneous auricular vagus nerve stimulation for a period of six weeks. Sham transcutaneous auricular vagus nerve stimulation will be carried out as an adjuvant, i.e. in addition to the regular treatment of the participants. The intervention will take place three times a day from Monday to Friday. Each of the three daily sessions is going to last 30-60 minutes. The procedures for sham tVNS will be identical to tVNS, with the only exception that the sham tVNS will be performed with no current output

Sponsors

Max-Planck-Institute of Psychiatry
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Caregiver, Investigator)

Intervention model description

Patients from the clinic of Max-Planck-Institute of Psychiatry are block wise randomly assigned to one of 2 study arms (transcutaneous auricular vagus nerve stimulation, sham transcutaneous auricular vagus nerve stimulation) after they have given informed consent

Eligibility

Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No

Inclusion criteria

1. age 18-65 years, legally competent and able to provide informed consent; 2. diagnosis of a depressive episode (MDD or bipolar disorder) according to DSM 4/DSM 5 or ICD-10/ICD-11; 3. signed informed consent documents for the AddVNS study; 4. signed informed consent and participation in the biobanking project of MPIP; 5. use of a safe contraceptive method

Exclusion criteria

1. age \< 18 years or age \> 65 years; 2. pregnancy or planning to get pregnant during the study period, breastfeeding; 3. legal supervision; 4. pervasive developmental disorders and/or intellectual disability; 5. acute substance abuse (e.g., alcohol, prescription or illicit drugs); 6. severe neurological disease; 7. technically or anatomically not possible tVNS (e.g., microtia or anotia, vagotomy); 8. current treatment with an established neurostimulation method (e.g., ECT, rTMS, VNS); 9. metallic foreign bodies, implanted intracranial devices or cerebral shunts; 10. severe general illness (e.g., relevant anemia requiring transfusion, high-grade cardiac arrythmia, severe cardiomyopathy); 11. active implants (e.g., cochlear implant, cardiac pacemaker, implantable cardioverter-defibrillator)

Design outcomes

Primary

MeasureTime frameDescription
Investigation of electrolyte changesBaseline, week 3, week 6Electrolyte changes over time (based on material extracted from peripheral blood)
Change from baseline in pupillometryBaseline, week 3, week 6Pupil diameter associated with the clinical response to tVNS
Change from baseline in 3-channel ECGBaseline, week 3, week 63-channel ECG associated with the clinical response to tVNS
Change from baseline in skin conductance levelBaseline, week 3, week 6Skin conductance level associated with the clinical response to tVNS
Change from baseline in photoplethysmographyBaseline, week 3, week 6Photoplethysmography associated with the clinical response to tVNS
Change from baseline in electrogastrogramBaseline, week 3, week 6Electrogastrogram associated with the clinical response to tVNS
Change from baseline in the functional status of brainstem nucleiBaseline, week 6Functional status of selected brainstem nuclei (by fMRI) associated with the clinical response to tVNS
Change from baseline in the response patterns in the reward anticipation taskBaseline, week 6Response patterns in the reward anticipation task (by fMRI) with the clinical response to tVNS
Change from baseline in motor activityContinuously starting from baseline up to week 6Motor activity changes, measured by actigraph, associated with the clinical response to tVNS
Change from baseline in heart rateContinuously starting from baseline up to week 6Heart rate, measured by actigraph, associated with the clinical response to tVNS
Change from baseline in heart rate variabilityContinuously starting from baseline up to week 6Heart rate variability, measured by actigraph, associated with the clinical response to tVNS
Change from baseline in oxygen saturationContinuously starting from baseline up to week 6Oxygen saturation, measured by actigraph, associated with the clinical response to tVNS
Change from baseline in skin temperatureContinuously starting from baseline up to week 6Skin temperature, measured by actigraph, associated with the clinical response to tVNS
Investigation of gene expression changesBaseline, week 3, week 6Gene expression changes over time (based on material extracted from peripheral blood)
Investigation of epigenetic changesBaseline, week 3, week 6Epigenetic changes over time (based on material extracted from peripheral blood)
Investigation of protein changesBaseline, week 3, week 6Protein changes over time (based on material extracted from peripheral blood)
Investigation of lipid changesBaseline, week 3, week 6Lipid changes over time (based on material extracted from peripheral blood)
Investigation of immunophenotypic changesBaseline, week 3, week 6Immunophenotypic changes over time (based on material extracted from peripheral blood)
Microbiome changesBaseline, week 3, week 6Microbiome changes (bacteria strains and metabolites) over time
GeneticsBaselineGenotyping based on material extracted from peripheral blood

Secondary

MeasureTime frameDescription
Change from baseline in the Global Assessment of Functioning (GAF)Baseline, week 3, week 6The GAF approximates the level of symptom burden and psychosocial as well as occupational functioning in daily life. It is tailored primarily to psychiatric patients. It is rated from 0 to 100 by a trained clinician. The GAF score is a continuous variable and allows to estimate symptom reduction and functional assessment from a foreign rater perspective
Change from baseline in Episodic memory testBaseline, week 6A short text is read aloud and the patient is asked to memorize the content. The patient is asked to repeat the text immediately after it has been read aloud and again after 30 minutes.
Change from baseline in the INHIB test (Response inhibition)Baseline, week 6INHIB is a test for response inhibition from the COGBAT basic cognitive testing. In this task, circles and triangles are preset. Whenever the triangle appears, the patient must press a button as quickly as possible (go trial), ignoring the circles (no-go trial).
Change from baseline in N-back-verbal test (NBV)Baseline, week 6N-back is a test for working memory from COGBAT basic cognitive testing. The patient is presented with a sequence of letters on a screen and should press a button when the presented letter is the same as the letter before.
Change from baseline in WAF test (perception and attention functions battery )Baseline, week 6WAF is a test baterry for the assessment of sub-functions of attention and is part of the COGBAT basic cognitive testing. In the AddVNS study the test for cross-modal visual /auditory attention and the test for intrinsic (visual) alertness are used. In the task for cross-modal visual/auditory attention, the patient concentrates simultaneously on a figure and on an auditory stimulus. The intensity of the stimuli changes at certain intervals. The patient must react as soon as one of the two stimuli becomes brighter or quieter twice in a row. In the task for intrinsic (visual) alertness, the patient has to press a button as quickly as possible as soon as a black circle appears on the screen.
Change from baseline in MWT-B test (multiple-choice vocabulary intelligence test B )Baseline, week 6MWT-B is a multiple choice vocabulary intelligence test. In this test, the patient is given 37 rows with five words each, only one of which actually exists and should be crossed out accordingly.
Change from baseline in the Hamilton Depression Rating Scale (HAM-D)Baseline, week 3, week 6The HAM-D measures the presence and severity of depression. Each of the items is rated by a study clinician or trained study staff member and added up to a summary score. Treatment response is generally defined by 50% score reduction, while remission is commonly assumed if the HAM-D score is ≤ 7 points
Change from baseline in the Montgomery-Åsberg Depression Rating Scale (MADRS)Baseline, week 3, week 6The MADRS measures the presence and severity of depression. Each of the terms is rated by a study clinician or trained study staff member and added up to a summary score. Treatment response is generally defined by 50% score reduction, while remission is commonly assumed if the MADRS score falls short of 12 points
Change from baseline in the Beck-Depression-Inventory II (BDI-II)Weekly up to week 6, week 12, week 18The BDI-II measures the presence and severity of depression symptoms on a mostly psychological and partially somatic level. Each of the 21 items is rated by the patient and added up to a summary score. Treatment response is generally defined by 50% score reduction, while remission is commonly assumed if the BDI-II score is ≤ 10 points
Change from baseline in the Patient Health Questionnaire 9 (PHQ-9)Weekly up to week 6, week 12, week 18The PHQ-9 is a brief measure of depression symptoms. Each of the 9 items is rated by the patient from 0 = not at all to 3 = nearly every day and added up to a summary score. Treatment response is generally defined by 50% score reduction, while remission is commonly assumed if the PHQ-9 score is ≤ 5 points.
Change from baseline in the Patient Health Questionnaire 15 (PHQ-15)Weekly up to week 6, week 12, week 18The PHQ-15 is a measure of somatic symptom load in psychiatric disorders. Each of the 15 somatic symptoms is rated by the patient from 0 = not affected to 2 = strongly affected and added up to a summary score. Cut-off values are ≥ 5points (mild), ≥ 10 points (moderate), ≥ 15 points (severe) and represent somatization.
Change from baseline in the Questionnaire on Mental Capacity (FLEI = Questionnaire for Complaints of Cognitive Disturbances )Weekly up to week 6, week 12, week 18The FLEI measures neurocognitive functioning in the following domains: attention, memory, executive function, control scale. Each of the 35 questions is answered by the patient from 0 = never to 4 = very often. Summary scores are computed for the different neurocognitive domains. Since the FLEI is primarily a continuous variable, symptom reduction is commonly assessed quantitatively
Change from baseline in the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0.) questionnaireBaseline, week 6, week 12, week 18The WHODAS 2.0. questionnaire is a self-rating instrument with 36 items for the assessment of health, functioning, disability and health-related quality of life which can be used across all diseases
Change from baseline in the Rejection Sensitivity Questionnaire (RSQ)Baseline, week 6, week 12, week 18The German modified version of RSQ with 20 items will be used as a measure of rejection sensitivity (RS) to explore the role of RS in the context of tVNS in depressive disorders.
Change from baseline in Snaith-Hamilton-Pleasure-Scale (SHAPS-D)Weekly up to week 6, week 12, week 18SHAPS-D is an instrument for the assessment of anhedonia. Each of the 14 items is rated by the patient and added up to a summary score. Anhedonia is commonly assumed if the SHAPS-D score is \> 2.
Change from baseline in Hamilton Rating Scale for Anixety (HAM-A)Baseline, week 3, week 6HAM-A is a rating scale for the assessment of anxiety symptoms. Each of the 14 items is rated by a study clinician or trained study staff and added up to a summary score with a total range from 0 to 56. Remission of anxiety is commonly assumed if the HAM-A score is ≤ 7.
Change from baseline in Trail Making Test Version A (TMT-A) and B (TMT-B)Baseline, week 6TMT is an attention test from COGBAT basic cognitive testing. In the A version, the patient is given the task of connecting circles with the numbers 1 to 25 as quickly as possible in ascending order. This is followed by the B version of the test, in which the patient has to connect circles with the numbers from 1 to 13 and letters from A to L alternatingly in ascending order.
Change from baseline in TOL-F test (Tower of London - Freiburg version)Baseline, week 6TOL-F is a test for planning ability from COGBAT basic cognitive testing. In this task, the patient must move balls on wooden sticks in the fewest number of moves possible so that the specified target condition is reached.

Other

MeasureTime frameDescription
Identification of clinical predictors of treatment response namely maladaptive personality traits measured by the German version of the Personality Inventory for DSM-5 and ICD-11 - brief form -version 1.1 (self-rating)BaselineLead to identification of maladaptive personality traits, no score on a scale.
Identification of clinical predictors of treatment response namely maladaptive personality traits measured by the Levels of Personality Functioning Scale-Brief Form 2.0 (self-rating)BaselineLead to identification of maladaptive personality traits, no score on a scale.
Sociodemographic variables (age, gender, marital status, income, education, occupation, family history of migration)BaselineSociodemographic variables as covariables for analysis of treatment response
Actual medicationweekly up to week 6Reporting of actual medication as covariable for analysis of treatment response
Medical history (psychiatric history, somatic medical history, family history, substance use history, medication history)BaselineMedical history as covariable for analysis of treatment response

Countries

Germany

Contacts

Primary ContactEvangelos Kokolakis, MD
ambulanz@psych.mpg.de0049-89-30622-1000
Backup ContactIven-Alex von Mücke-Heim, MD, MSc
ambulanz@psych.mpg.de0049-89-30622-1000

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026