Phase 2 Trial of Tributyrin in People With Parkinson's Disease and Cognitive Impairments (BUTTER2)

November 10, 2025 updated by: Prabesh Kanel

The goal of this clinical trial is to learn if taking a tributyrin supplement works to improve memory and thinking and walking and balance in adults with Parkinson disease Parkinson disease dementia. It will also learn about the safety of tributyrin supplementation. The main questions it aims to answer are:

  1. Does tributyrin improve memory/thinking test scores and walking/balance ability?
  2. What medical problems do participants have when taking tributyrin?

Researchers will compare tributyrin to a placebo (a look-alike substance that contains no drug) to see if tributyrin works to treat Parkinson disease symptoms.

Participants will:

  1. Take tributyrin 3 times a day for 80-100 days
  2. Complete motor and cognitive testing at the clinic before and after the supplementation period
  3. Complete brain imaging (MRI scans and PET scans) before and after the supplementation period.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Changes in cognition, progressing usually to dementia, are common features of Parkinson disease (PD). These debilitating impairments respond poorly to current anti-dementia treatments and call for novel strategies. Short chain fatty acids (SFCA), in particular butyric acid (BA), are naturally present in the colon as a bacterial product of dietary fiber fermentation. There is renewed interest in SCFAs because of their potential as alternative substrates in brain metabolism, their role in the gut-brain axis, and emerging evidence that interventions promoting SCFA benefit patients with neurodegenerative disorders. Convergent evidence suggests that SFCAs may ameliorate metabolic defects secondary to mitochondrial abnormalities in PD. In addition, the gut-brain axis represents a bidirectional communication complex system involving the vagal and sympathetic nerves and humoral systems. Effects of SCFA on the brain may be indirect and/or direct. For example, fiber-induced SCFA production in the colon may result in vagal nerve-mediated changes affecting the brain. Blood and brain levels of fiber-induced SCFA are naturally very low. SCFAs can be directly administered orally, resulting in higher portal vein and systemic plasma levels that may more potently affect brain functions. Oral butyrate supplementation, however, suffers from several limitations as plasma levels are low because of rapid metabolism. In contrast, tributyrin (the triglyceride of BA) is rapidly absorbed and chemically stable in plasma, diffuses through biological membranes and is metabolized by intracellular lipases, releasing therapeutically effective BA over time directly within cells. We previously generated target engagement data showing that oral tributyrin, 500 mg three times per day (tid) po, is well tolerated and improves cognition. We also conducted the first [11C]butyrate positron emission tomography (PET) study, demonstrating that tributyrin has direct brain effects, particularly in regions relevant to cognitive functions. Significant systemic anti-inflammatory effects were also observed. A limitation of our preliminary phase 1I target engagement study is the short duration (30 days) and lack of inclusion of people with PD with more severe cognitive impairments, such as dementia. The overarching goal of this project is to perform a parallel group, double-blinded, randomized placebo-controlled phase 2 clinical trial of tributyrin, 500 mg tid po for 90 days, to validate and extend these preliminary observations in a longer duration clinical trial in people with PD with mild cognitive impairment (PD-MCI) or Parkinson disease dementia (PDD). There is critical unmet clinical need to treat people currently affected with PD who have significant cognitive impairments. Our main hypothesis is that oral tributyrin supplementation will improve cognition as well as motor functions, including cognition-dependent postural instability and gait difficulties. Successful completion of this trial would set the stage for a major, multi-center phase III clinical trial aimed at ameliorating this particularly morbid feature of PD.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
45

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Michigan
      • Ann Arbor, Michigan, United States, 48105
        • Recruiting
        • Domino's Farms
        • Contact:
        • Principal Investigator:
          • Prabesh Kanel, PhD
        • Sub-Investigator:
          • Nicolaas Bohnen, MD, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Male or Female, age 45 years and over.
  • Diagnosis of PD based on the United Kingdom Parkinson's Disease Society Brain Bank Diagnostic Research Criteria (Hughes et al., 1992) AND evidence of mild cognitive impairment (Litvan et al., 2012) OR Diagnosis of PDD (Emre et al., 2007).
  • If taking cholinesterase inhibitors, benzodiazepines, memantine, or anti-psychotic medications, on a stable regimen as defined by no medication changes for these drugs in prior 4 weeks.

Exclusion Criteria:

  • Evidence of atypical parkinsonism.
  • Contra-indications to MR imaging including but not limited to pacemakers, aneurysm clips, intraocular metal, cochlear implant, or severe claustrophobia.
  • Evidence of large vessel stroke or mass lesion on MRI.
  • Regular use of typical anti-cholinergic drugs.
  • Recent history of significant, uncontrolled GI disease such as GERD, colorectal cancer.
  • Significant metabolic or uncontrolled medical comorbidity.
  • Pregnant or nursing.
  • Suicidal ideation, as indicated by a response of 2 or 3 on question 9 of the Beck Depression Inventory.
  • Any other condition or criterion that would preclude safe and meaningful participation in the study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Tributyrin Supplementation
Participants will take 500mg TID tributyrin supplement for 90 days +/- 7 days.
Drug: Tributyrin
Post-biotic short chain fatty acid dietary supplement. Participants will take 500mg TID tributyrin supplement for 90 days +/- 7 days.
Placebo Comparator: Placebo
Participants will take 500mg placebo for 90 days +/- 7 days.
Drug: Placebo
Participants will take 500mg TID placebo for 90 days +/- 7 days.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Single composite global cognitive z-score
Time Frame: Baseline and post-intervention (83-97 days after starting supplement)
A global cognitive z-score derived from a neuropsychological battery including the California Verbal Learning Test (short- and long-term memory), Delis-Kaplan Executive Function System (verbal fluency via letter fluency test, executive function via Stroop and Trail Making Test Part 4), and Benton Judgment of Line Orientation Test (visuospatial cognition). Individual test scores are normatively z-scored with age- and sex-adjustment using data from 55 cognitively normal controls (Montreal Cognitive Assessment score > 25). All z-scores are aligned so that higher scores indicate better performance. Scores are averaged within domains and then across domains to compute the global cognitive z-score.
Baseline and post-intervention (83-97 days after starting supplement)
Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III Score
Time Frame: Baseline and post-intervention (83-97 days after starting supplement)
Movement Disorder Society Unified Parkinson's Disease Rating Scale Part 3 (MDS-UPDRS part III) is the motor examination portion of the UPDRS evaluation. Scores range from 0-132, with higher scores indicating greater severity of motor symptoms.
Baseline and post-intervention (83-97 days after starting supplement)
Safety and tolerability of tributyrin
Time Frame: During and after 83-97 day supplementation period
Safety and tolerability are assessed by monitoring the incidence, severity, and relationship of adverse events (AEs), serious adverse events (SAEs), and discontinuations due to AEs. AE information via biweekly phone-call monitoring, and during the post-intervention study visit.
During and after 83-97 day supplementation period

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Prabesh Kanel

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Farmer Family Foundation

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Prabesh Kanel, PhD, University of Michigan

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 7, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 26, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 26, 2025

First Posted (Estimated)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 4, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 12, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 10, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • HUM00270219

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

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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