Ear vagus nerve stimulation to improve motivation and insulin sensitivity
Acute Effects of Non-invasive Vagus Nerve Stimulation on Motivation and Its Dependency on Insulin Sensitivity in Patients With Depression and Controls
This trial will test whether short sessions of non-invasive ear vagus nerve stimulation can improve motivation and mood in adults with major depression and whether a person’s insulin sensitivity changes those effects.
Quick facts
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 120 (estimated) |
| Ages | 18 Years to 60 Years |
| Sex | All |
| Sponsor | University of Bonn Academic / other |
| Locations | 1 site (Bonn) |
| Trial ID | NCT07198100 on ClinicalTrials.gov |
What this trial studies
The study will enroll 60 adults with major depressive disorder and 60 matched control participants across a wide BMI and insulin-sensitivity range, including people with type 2 diabetes. Participants complete an intake with clinical interviews, fasting blood work, and a battery of reward and effort tasks, then wear a continuous glucose sensor and complete ecological momentary assessments for two weeks. Insulin sensitivity is measured with an oral glucose tolerance test while participants receive randomized acute transcutaneous auricular vagus nerve stimulation (tVNS) versus sham on separate days, and two randomized neuroimaging sessions use concurrent fMRI and electrogastrography to measure brain and stomach responses. The design is single-blind (participants), includes a minimum 2-day washout between stimulation conditions, and collects additional metabolic, questionnaire, and optional genetic biobank data to characterize participants.
Who should consider this trial
Good fit: Ideal participants are adults aged 18–60 with BMI 18.5–40 kg/m² who either have a DSM-5 diagnosis of major depressive disorder or are matched healthy controls, and who can undergo MRI, oGTT, blood draws, and wear a glucose sensor.
Not a fit: People with contraindications such as MRI-incompatible implants, ear conditions that prevent taVNS, type 1 diabetes, recent severe psychiatric disorders (eg, bipolar disorder, schizophrenia), or major cardiac/neurological conditions are unlikely to benefit or cannot participate.
Why it matters
Potential benefit: If successful, this could offer a non-invasive way to boost motivation and mood, particularly for patients whose metabolic state (insulin resistance) contributes to anhedonia.
How similar studies have performed: Preclinical work and some clinical tVNS studies have shown promising effects on mood and motivation, but combining acute tVNS with insulin-sensitivity testing and stomach–brain coupling measurements is a relatively novel approach.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion criteria: * Participants with depression (DSM-5 diagnosis) or participants without depression (no DSM-5 diagnosis, lifetime) * BMI between 18.5 and 40 kg/m² * Age between 18 and 60 years * Legally valid informed consent Exclusion criteria: The following diagnoses in medical history: * Brain injury * Schizophrenia * Bipolar disorder * Severe substance use disorder * Coronary heart disease * Stroke * Epilepsy * Chronic inflammatory diseases (e.g., rheumatoid arthritis, Crohn's disease, etc.) * Type I diabetes The following diagnoses within 12 months prior to the experiment: * Obsessive-compulsive disorder * Somatic symptom disorder * Eating disorder The following diagnoses in medical history for control participants: * Depression * Anxiety disorders (except specific phobias) Generally: * Contraindications for MRI (e.g., metal implants, claustrophobia) or taVNS (e.g., piercings, sore or diseased skin on the outer right ear) * Pregnant and breastfeeding women will not be included * Unclear capacity to consent * Stomach surgeries affecting body weight (e.g., bypass surgeries)
Where this trial is running
Bonn
- Section of Medical Psychology, Department of Psychiatry & Psychotherapy, Faculty of Medicine, University of Bonn — Bonn, Germany (Recruiting)
Study contacts
- Principal investigator: Nils B Kroemer, Prof. Dr. — Section of Medical Psychology, Department of Psychiatry & Psychotherapy, Faculty of Medicine, University of Bonn, 53127 Bonn, Germany
- Study coordinator: Nils B Kroemer, Prof. Dr.
- Email: nkroemer@uni-bonn.de
- Phone: +49 228 287 11151
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.