Tests a non-invasive ear nerve stimulation device for motivation in depression
Tests ear vagus nerve stimulation on motivation in adults with depression and controls.
Plain-language title generated from the registry record
Registry title: tVNS, Motivation, and Insulin Sensitivity
Key facts
- Where
- Bonn, GermanySee the site
Could this be for you?
Answer for yourself. This is not a decision: only the study team can say whether you can take part.
- Are you between 18 and 60 years old?
Source: NCT07198100, who can take part
Where in Germany
- Section of Medical Psychology, Department of Psychiatry & Psychotherapy, Faculty of Medicine, University of BonnBonn, GermanyTaking people
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Trial details
- Who runs it
- University of Bonn
- Trial code
- NCT07198100
- Record updated
- 24 December 2025
- Original description
Disturbances in energy metabolism significantly increase the risk of developing major depressive disorder (MDD), especially in individuals with type 2 diabetes. Insulin sensitivity may particularly impair reward anticipation and motivational processes, contributing to anhedonia, a core symptom of depression. Preclinical and clinical studies highlight the vagus nerve as a critical pathway mediating metabolic signals between the body and the brain, influencing motivational and affective states.Read full original descriptionShow less
Acute Effects of Non-invasive Vagus Nerve Stimulation on Motivation and Its Dependency on Insulin Sensitivity in Patients With Depression and Controls
Disturbances in energy metabolism significantly increase the risk of developing major depressive disorder (MDD), especially in individuals with type 2 diabetes. Insulin sensitivity may particularly impair reward anticipation and motivational processes, contributing to anhedonia, a core symptom of depression. Preclinical and clinical studies highlight the vagus nerve as a critical pathway mediating metabolic signals between the body and the brain, influencing motivational and affective states.
The present study aims to evaluate whether acute transcutaneous auricular vagus nerve stimulation (taVNS) improves motivation and mood and whether individual differences in insulin sensitivity modulate these improvements.
The investigators plan to recruit 60 patients with MDD and 60 control participants matched for age, sex, and body mass index (BMI), covering a wide BMI range (up to 40 kg/m²) and insulin sensitivity (including patients with type 2 diabetes). Participants will undergo comprehensive metabolic assessments, behavioral testing of reward anticipation, motivation, consummation, and learning, and ecological momentary assessments (EMA) coupled with continuous glucose monitoring to assess real-world motivational behavior and glucose dynamics. Furthermore, participants will undergo two neuroimaging sessions, involving both task-free and task-based functional MRI, during concurrent taVNS or sham stimulation, implemented in a randomized, single-blinded, crossover design.
This study hypothesizes that individuals with lower insulin sensitivity, particularly those with MDD and pronounced anhedonic symptoms, will show greater motivational and neural responsiveness to taVNS.
H1A. Individuals with depression (vs. controls) and higher anhedonia show greater deficits in reward-related behavior and lower insulin sensitivity.
H1B. Across all participants, reduced reward-related behavior and higher anhedonia are associated with lower insulin sensitivity.
H2A. tVNS (vs. sham) increases motivation for rewards, brain responses to rewards, and body-brain interactions across participants.
H2B. These tVNS-induced effects are particularly pronounced in individuals with depression and stronger anhedonia who show reductions in these domains.
H3A. Greater tVNS-induced effects (behavioral, neural, body-brain) are associated with lower insulin sensitivity.
Inclusion: 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: Type I diabetes; The following diagnoses within 12 months prior to the experiment:; Contraindications for MRI (e.g., metal implants, claustrophobia) or taVNS (e.g., piercings, sore or diseased skin on the outer right ear); Bipolar disorder; Severe substance use disorder; Coronary heart disease; Stroke; Epilepsy; Chronic inflammatory diseases (e.g., rheumatoid arthritis, Crohn's disease, etc.); Obsessive-compulsive disorder; Somatic symptom disorder; Eating disorder; The following diagnoses in medical history for control participants:; Anxiety disorders (except specific phobias); Generally:; The following diagnoses in medical history:; Brain injury; Schizophrenia; Depression; Pregnant and breastfeeding women will not be included; Unclear capacity to consent; Stomach surgeries affecting body weight (e.g., bypass surgeries).