Effects of nVNS on Stress Reactivity in IBS

Trial details

Who runs it

University of California, Los Angeles

Trial code

NCT07926945

Record updated

9 November 2026

Original description

Irritable bowel syndrome (IBS) is a chronic disorder of gut-brain interaction that causes abdominal pain and altered bowel habits. Many people with IBS also experience symptoms outside the bowel, such as headaches, widespread pain, poor sleep, anxiety, and depression; these symptoms are especially common in females. This study focuses on stress reactivity (SR), a persistent pattern of stress-system activity that may be linked to autonomic nervous system function, immune activity, the gut microbiome, and brain processing. The investigators will enroll adults with at least moderate IBS symptoms and randomly assign them to 8 weeks of non-invasive vagal nerve stimulation (nVNS) or Usual Care. Participants assigned to nVNS will use a handheld device on the left side of the neck at home twice daily. The investigators will compare changes in IBS severity and other physical symptoms and examine whether baseline or treatment-related changes in blood, stool, heart-rate variability, sex hormones, and brain imaging measures are associated with response. The study will also explore whether treatment effects and predictors differ by sex.Read full original descriptionShow less

Effects of Non-invasive Vagal Nerve Stimulation on Clinical, Peripheral Biologic, and Brain Measures of Stress Reactivity in Irritable Bowel Syndrome: a Randomized Controlled Trial

Irritable bowel syndrome (IBS) is a chronic disorder of gut-brain interaction that causes abdominal pain and altered bowel habits. Many people with IBS also experience symptoms outside the bowel, such as headaches, widespread pain, poor sleep, anxiety, and depression; these symptoms are especially common in females. This study focuses on stress reactivity (SR), a persistent pattern of stress-system activity that may be linked to autonomic nervous system function, immune activity, the gut microbiome, and brain processing. The investigators will enroll adults with at least moderate IBS symptoms and randomly assign them to 8 weeks of non-invasive vagal nerve stimulation (nVNS) or Usual Care. Participants assigned to nVNS will use a handheld device on the left side of the neck at home twice daily. The investigators will compare changes in IBS severity and other physical symptoms and examine whether baseline or treatment-related changes in blood, stool, heart-rate variability, sex hormones, and brain imaging measures are associated with response. The study will also explore whether treatment effects and predictors differ by sex.

Inclusion: Age 18-50 years; Meets Rome V diagnostic criteria for IBS-D or IBS-M; At least moderate IBS symptom severity, defined as IBS-SSS ≥175; For females: premenopausal with generally regular menstrual cycles and willing to complete study visits within the study-specified menstrual-cycle window when feasible; Able to understand and provide informed consent in English; Willing and able to complete questionnaires, biospecimen collection, wearable monitoring, MRI procedures, and randomized study requirements.

Exclusion: Evidence or history of another gastrointestinal disease that could explain symptoms, including inflammatory bowel disease or celiac disease, unless adequately excluded by clinical evaluation or prior testing; Previous use in the last 3 months OR current use of hormonal medications, including hormonal contraceptives (i.e. birth control pills, patches, implants, or intrauterine devices (IUDs)) or hormone replacement therapy; MRI contraindication, including a non-removable ferromagnetic implant or device, prior significant tattoo-related heating or burns, severe claustrophobia that cannot be managed, or another condition judged unsafe for MRI; Past abdominal surgery (except for appendectomy, cholecystectomy, benign polypectomy, hiatus hernia); Major active psychiatric illness (e.g., schizophrenia, bipolar disorder), significant neurologic or central nervous system disease, or another medical condition that could affect safety, adherence, or interpretation of study outcomes; Dermatologic conditions affecting the neck region that would interfere with nVNS placement; History of cervical vagotomy; Movement disorder; Clinically significant hypertension, hypotension, bradycardia, or tachycardia; Cardiac disease or atherosclerotic cardiac disease, including congestive heart failure, known severe coronary artery disease, or recent myocardial infarction within 5 years; Individuals with obesity (BMI > 30); Pregnancy or a positive pregnancy test; Perimenopausal or postmenopausal status; Current participation in another IBS-specific intervention study or planned initiation of a new IBS-directed treatment during the 8-week randomized period; Contraindication to cervical nVNS or inability to use the device safely; Any implanted electrical device; Any metallic device implanted at or near the neck; Use of another electrical device at the same time (e.g., TENS unit, muscle stimulator) or any portable electronic device; Inability or unwillingness to provide informed consent or complete study procedures in English.

ClinicalTrials.gov NCT07926945