Probing Gut-Brain Communication in Parkinson's Disease

Administering transcutaneous vagus nerve stimulation in patients with Parkinson's disease to see how it affects stomach and brain activity.

Study Overview

• Status: Not yet recruiting
• Conditions: Parkinson Disease (PD)
• Intervention / Treatment: Device: taVNS; Device: Sham taVNS

• Study Type: Interventional
• Enrollment (Estimated): 45
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Noah Naddaff-Slocum, BA; Phone Number: 617-724-6086; Email: nnaddaff-slocum@mgh.harvard.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Aged ≥21 years old and ≤80 years old
• Clinical diagnosis of PD as defined by Movement Disorder Society (MDS) PD Criteria
• Adequate visual, hearing, cognitive, and physical ability

Exclusion Criteria:

• Diagnosis of secondary or atypical parkinsonism
• Laboratory Values: a: Hemoglobin (Hgb) <10; b: Platelets <70,000; c: Alanine Transaminase (ALT) or Aspartate Aminotransferase (AST) > 2 1/2 times upper limit of normal (ULN); d: Moderate or severe renal disease with an estimated glomerular filtration rate (eGFR) <60 mL/min/BSA [body surface area] calculated using the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation, or moderate or severe hepatic impairment (alkaline phosphatase [ALP] >2.0 times the ULN and/or total bilirubin >2.0 times the ULN); e: Significantly above the normal range for PT/INR/PTT.
• Clinically significant cognitive impairment with a Montreal Cognitive Assessment (MOCA) score 35 kg/m2 or body weight
• Clinical or laboratory findings consistent with another primary neurodegenerative disease or cognitive disorder other than PD, including but not limited to, frontotemporal lobar disease, Huntington's disease, progressive supranuclear palsy, multisystem atrophy, Creutzfeld-Jakob- Disease, Down's syndrome, cortico-basal degeneration, dementia with Lewy Bodies, Alzheimer's disease, amyotrophic lateral sclerosis, seizure disorder, stroke, or other infectious, metabolic, or systemic disease affecting the central nervous system including, but not limited to, syphilis, present hypothyroidism, present or unaddressed/treated vitamin B12 deficiency, or other screening laboratory abnormalities
• Suicidality, defined as active suicidal thoughts or ideation within 6 months before Screening or at Baseline, defined as answering yes to items 4 or 5 on the Columbia-Suicide Severity Rating Scale (C-SSRS), or history of suicide attempt in previous 2 years, or, in the Investigator's opinion, at serious risk of suicide
• Has cancer or has had a malignant tumor within the past 5 years. (Participants with stable untreated prostate cancer or treated cutaneous squamous or basal cell carcinomas are not excluded.)
• Any medical condition or systemic disease that, in the Investigator's opinion, may either put the participant at risk because of participation in the study, influence the results or proposed analyses, or impair the participant's ability to fully participate in the study
• Body weight > 400lbs (limit of the MRI table)
• Participant is currently pregnant, breastfeeding, and/or lactating
• History of alcohol or substance abuse or dependence within the past 2 years (DSM IV criteria)
• History of Covid-19 (SARS-CoV-2) infection within 6 weeks prior to screening.
• Participants with unresolved symptoms of Covid-19 infection or ongoing cognitive or other deficits attributable to post-Covid-19 that may affect participant safety or interfere with cognitive assessments based on the Investigator's clinical judgment
• Either ongoing or current participation in another clinical trial with an investigational agent and have taken at least one dose of study medication, unless unblinded on placebo, within 4 weeks prior to the start of screening, or five half-lives of the investigational drug, whichever is greater. The end of a previous investigational trial is the date the last dose of an investigational agent was taken. Participation in other research studies (e.g., observational studies) may be acceptable throughout this study.
• History of GI surgery. (However, patients with appendicectomy, hemorrhoid surgery, and cholecystectomy will be eligible to participate).
• Use of medications that impact the microbiota including antibiotics during the 4 weeks prior to enrollment
• Regular use of medication that impacts the intestinal barrier (e.g., NSAID more than 3 times weekly)
• Endorses any contraindications to MRI (see risks section of protocol for full list of MRI exclusions)
• Allergic to pineapple

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: taVNS; Active taVNS	Device: taVNS; Active taVNS delivered to the external ear at a moderate, non-painful level.
Sham Comparator: Sham taVNS	Device: Sham taVNS; Sham taVNS delivered to the external ear using zero-current.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gastric outcomes (accommodation and emptying) during UROstim administration as measured by gastric MRI	The study team will be measuring and comparing how the stomach responds to food (how much it expands and how quickly it empties) when the participant has stimulation delivered right after eating vs. having sham delivered right after eating.	From enrollment until the completion of their final visit, which will not exceed a duration of 4 weeks.
Brain activity during UROstim administration as measured by fMRI	The study team will be investigating how brain activity and connectivity differs when the subject experiences vagus nerve stimulation vs. sham stimulation.	From enrollment to the end of their study participation, typically 4 weeks.

Collaborators and Investigators

• Sponsor: Spaulding Rehabilitation Hospital
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): July 1, 2031
• Study Completion (Estimated): July 1, 2031

Study Registration Dates

• First Submitted: June 10, 2026
• First Submitted That Met QC Criteria: June 22, 2026
• First Posted (Actual): June 29, 2026

Study Record Updates

• Last Update Posted (Actual): July 2, 2026
• Last Update Submitted That Met QC Criteria: June 30, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Synucleinopathies; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurodegenerative Diseases; Movement Disorders; Parkinsonian Disorders; Basal Ganglia Diseases; Parkinson Disease
• Other Study ID Numbers: 2026P001274; U01DK140933 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No