tVNS and Approach-Avoidance Behavior in Anhedonia and Anxiety

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.

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)

Interventions

DEVICE

tVNS

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.

DEVICE

Sham

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.

Sponsors & Collaborators

• University of Bonn

  collaborator OTHER

• Else Kröner Fresenius Foundation

  collaborator OTHER

• Dr. Nils B. Kroemer

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

40 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2026-03-23

Primary Completion

2027-12-31

Completion

2028-12-31

Countries

• Germany

Study Locations