Serotonin Variants & Gut Microbiota in Mental Health: Pilot Study

June 4, 2026 updated by: Neurobiologix

Association Between Serotonin Pathway Genetic Variants and Tryptophan-Metabolizing Gut Microbiota in Adults With Mental Health Conditions: An Observational Pilot Study

This observational pilot study investigates whether a broad panel of genetic variants relevant to the serotonin pathway (including serotonergic system, methylation cycle, intestinal barrier integrity, and inflammatory response genes) are associated with distinct gut microbiome compositional and functional signatures in adults aged 18-44 years with self-reported mental health conditions (Major Depressive Disorder, Generalized Anxiety Disorder, PTSD, or Panic Disorder).

This is a decentralized, participant-funded (Citizen Science) study. Eligible participants provide at-home saliva (buccal swab) and stool samples. Genomic analysis is performed using the NeuroBiologix GenePro+ SNP Panel (Illumina Infinium Global Screening Array-24, ~654,000 SNPs) via Gene By Gene, a CLIA/CAP-accredited laboratory. Gut microbiome analysis is performed by Tiny Health using deep whole-genome shotgun metagenomics (≥20 million reads) on a NextGen Illumina Platform.

The study is non-interventional and hypothesis-generating, aiming to identify potential genotype-microbiome associations and estimate effect sizes to inform a future interventional trial. N=30 participants. Study Start: July 2026.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Background: The gut-brain-microbiota axis (GBA) represents a complex, bidirectional communication system. Microbial tryptophan metabolism is a key mechanism within this axis - approximately 95% of the body's serotonin is synthesized peripherally in the gut. Host genetic variants can influence both serotonin biology and gut microbiome composition.

Objective: To explore correlations between multi-system genetic variants (TPH2, SLC6A4, MTHFR, FUT2, MUC1, IL-6, and others) and gut microbiome compositional and functional profiles (particularly tryptophan metabolism pathways) in adults with self-reported mental health conditions.

Design: Decentralized observational pilot study. Participants complete digital questionnaires and provide at-home biospecimen collections (saliva and stool) using prepaid medical-grade kits.

Genomic Methodology: Saliva samples undergo DNA extraction and array-based genotyping (Illumina GSA-24 v3.0) at Gene By Gene (CLIA No. 45D1102202, CAP-accredited). Data processed via OmicsEdge bioinformatics platform.

Metagenomic Methodology: Stool samples analyzed by Tiny Health using whole-genome shotgun metagenomics. Human reads are depleted against GRCh38. Taxonomic profiling via GTDB/GenBank database (111,000+ genomes). Functional annotation via KEGG Orthology and CAZy.

Statistical Analysis: Descriptive statistics; alpha diversity (Shannon index); beta diversity (Bray-Curtis dissimilarity); PERMANOVA; exploratory non-parametric comparisons between genotype-defined groups. Effect sizes calculated for future study design.

IRB: Approved by Sterling Institutional Review Board (Atlanta, GA), IRB ID 16153.

Study Type

Observational

Enrollment (Estimated)

30

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

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

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

N/A

Sampling Method

Non-Probability Sample

Study Population

US adults aged 18-44 years with self-reported MDD, GAD, PTSD, or Panic Disorder. Recruited via Neurobiologix and Tiny Health digital platforms and social media. Decentralized, direct-to-participant model.

Description

Inclusion Criteria:

  1. Age: Adults aged 18 to 44 years.
  2. Residency: Current legal residents of the United States.
  3. Clinical Phenotype: Self-report of Major Depressive Disorder (MDD), Generalized Anxiety Disorder (GAD), Post-Traumatic Stress Disorder (PTSD), or Panic Disorder.
  4. Medication Stability: If currently prescribed psychotropic medications (e.g., SSRIs, SNRIs, benzodiazepines), the dosage must remain stable with no changes in molecule or quantity for at least 3 months prior to enrollment.
  5. Language and Technology: Proficiency in English and access to a smartphone or computer for digital data entry.
  6. Financial Commitment: Explicit agreement to the "Citizen Science" model, including payment for discounted testing kits. Kit shipping (both directions) is prepaid by the study.

Exclusion Criteria:

  1. Use of systemic antibiotics, antifungals, or antivirals within the 8 weeks prior to specimen collection.
  2. Regular use of commercial probiotics or concentrated prebiotic supplements within 4 weeks of collection.
  3. Frequent use of osmotic or stimulant laxatives, or motility agents, within 4 weeks of collection.
  4. Chronic use (>3 times/week) of NSAIDs, systemic corticosteroids, or high-dose Omega-3 supplementation (>2g/day) within 4 weeks of enrollment.
  5. Use of weight-loss medications or GLP-1 receptor agonists (e.g., semaglutide, liraglutide, tirzepatide) within the 3 months prior to enrollment.
  6. Confirmed diagnosis of Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease (Crohn's or Ulcerative Colitis), Celiac Disease, or history of major gastric/intestinal resection.
  7. Current pregnancy or lactation.
  8. Presence of cognitive impairments that preclude the ability to provide informed consent.
  9. Individuals undergoing active cancer treatment.

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

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Adults with Mental Health Conditions
US adults aged 18-44 years with self-reported MDD, GAD, PTSD, or Panic Disorder who are on stable psychotropic medication (or unmedicated). Participants provide at-home saliva and stool samples for genomic SNP analysis (NeuroBiologix GenePro+ SNP Panel) and gut microbiome shotgun metagenomics sequencing (Tiny Health platform).
Diagnostic test: SNP Genotyping and Gut Metagenomics
Genomic analysis using NeuroBiologix GenePro+ SNP Panel: Illumina Infinium Global Screening Array-24 v3.0 (~654,000 SNPs), genotyped at Gene By Gene (CLIA No. 45D1102202, CAP-accredited). Data processed via OmicsEdge bioinformatics platform analyzing serotonergic, methylation, intestinal barrier, and inflammatory pathway variants. Gut microbiome analysis using Tiny Health deep whole-genome shotgun metagenomics (NextGen Illumina Platform, ≥20 million reads), with taxonomic profiling (GTDB/GenBank) and functional annotation (KEGG Orthology, CAZy).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Gut Microbiome Compositional and Functional Profile
Time Frame: At study completion (approximately 8-12 weeks after enrollment)
Shotgun metagenomic sequencing of stool samples to assess gut microbial taxonomic composition (alpha and beta diversity) and functional potential, specifically tryptophan metabolism pathways (KEGG Orthology), and their association with host genetic variants in the serotonin pathway.
At study completion (approximately 8-12 weeks after enrollment)

Collaborators and Investigators

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

Sponsor

Neurobiologix

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 (Estimated)

July 1, 2026

Primary Completion (Estimated)

July 1, 2027

Study Completion (Estimated)

September 1, 2027

Study Registration Dates

First Submitted

June 4, 2026

First Submitted That Met QC Criteria

June 4, 2026

First Posted (Actual)

June 8, 2026

Study Record Updates

Last Update Posted (Actual)

June 8, 2026

Last Update Submitted That Met QC Criteria

June 4, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 16153

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared due to the sensitive nature of genomic and mental health data. De-identified aggregate data and findings will be reported in peer-reviewed publications.

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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