RecruitingNot ApplicableNCT07476469

tVNS and Approach-Avoidance Behavior in Anhedonia and Anxiety

Vagus Nerve Stimulation and Approach-Avoidance Behavior in Anhedonia and Anxiety

Sponsor

Dr. Nils B. Kroemer

Enrollment

104 participants

Start Date

Mar 23, 2026

Study Type

INTERVENTIONAL

Conditions

Healthy Participants Anxiety Disorders (With High Anxiety Symptoms)Depressive Disorders (With High Anhedonia Symptoms)Comorbid Depression and Anxiety Disorder (With High Anhedonia and High Anxiety Symptoms)

Summary

This study investigates if anhedonia and anxiety symptoms are associated with alterations in reinforcement learning, effort trade-offs for wins vs. punishments, and foraging behavior under threat. Moreover, it will investigate whether these processes can be influenced by a metabolic load and/or transcutaneous vagus nerve stimulation (tVNS). The project consists of (a) an online reinforcement learning study, used to characterize learning, reward sensitivity, and meta-cognition, and (b) a laboratory study in which participants first undergo fMRI while completing an effort-based decision-making task. Second, participants will complete two sessions in VR with randomized active or sham tVNS during a foraging task before and after a caloric load with concurrent physiological recordings.

Eligibility

Min Age: 18 YearsMax Age: 40 Years

Inclusion Criteria3

BMI between 18,5 and 30,0 kg/m2,
between 18 and 40 years of age, and
be able and willing to provide informed consent.

Exclusion Criteria9

have a high risk of suicide,
have a lifetime diagnosis of severe neurological disorder (incl. ADHD), schizophrenia, bipolar disorder, or severe substance abuse, posttraumatic stress disorder, obsessive-compulsive disorder, diabetes, epilepsy, or coronary heart disease
have fulfilled criteria for an eating disorder or somatic symptom disorder within the last 12-months,
take medication (except psychopharmacological medication for MDD or anxiety), patients have to be on stable psychopharmacological medication for at least two months before study participation (minimizing confounding effects)
contraindications for MRI (metal implants or claustrophobia)
for female individuals if they are pregnant or nursing at the time,
impaired movement ability or hearing
impaired, uncorrected vision (need contact lenses)
contraindications for tVNS hearing aids or diseased skin on the right ear.

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Interventions

DEVICEtVNS

The intervention consists of event-triggered tVNS in the form of short pulses (\~1-5s; frequency: 25Hz). A non-CE-certified and non-medical device (tVNS® R tVNS technologies, for research purposes) will be used. Stimulation intensity will be individually calibrated to ensure perceptible (mild pricking) but non-painful stimulation for each participant. The protocol is the same for all groups.

DEVICESham

The sham condition similarly consists of event-triggered, closed-loop stimulation, but without vagus nerve activation (short pulses of 1-5s; frequency: 25Hz). A non-CE-certified and non-medical device (tVNS® R, for research purposes) will be used. The manufacturer is not involved in the study. Stimulation intensity will be individually calibrated to ensure perceptible (mild pricking) but non-painful stimulation for each participant. The protocol is the same for all groups.