Investigation of Pathogenic Gut Microbiota Patterns in Anxiety, Depression and Panic Disorders

This study aims to investigate the etiology of anxiety, depression, and panic disorders, providing new evidence and insights into the root causes and effective treatments, potentially offering a novel approach to achieving complete recovery.

Study Overview

• Status: Completed
• Conditions: Depression; Mood Disorders; Anxiety; Panic Disorder
• Intervention / Treatment: Diagnostic test: H pylori stool test; Diagnostic test: Bacterial stool analysis

Detailed Description

Background: Anxiety, depression and panic disorders are among the most prevalent mental health conditions globally, affecting millions and imposing a substantial burden on individuals, families, and healthcare systems. These disorders often manifest through recurrent, severe episodes of anxiety and fear, frequently accompanied by physical symptoms such as palpitations, chest pain, and dizziness, which can lead to significant functional impairment and diminished quality of life. While current treatment options include pharmacotherapy and cognitive-behavioral therapy, response rates vary, and many patients experience residual symptoms or adverse effects, leading to high rates of treatment discontinuation. Furthermore, the growing recognition of treatment-resistant anxiety, depression and panic disorders highlights an urgent need for innovative, evidence-based therapies that provide sustained relief without compromising safety.

Introduction Anxiety, depression and panic disorders are pervasive and debilitating chronic mental health conditions, affecting approximately 20% of the global population over a lifetime. Characterized by episodes of intense fear and physical symptoms such as heart palpitations, shortness of breath, and dizziness, these disorders can severely impact daily functioning, interpersonal relationships, and overall quality of life. Individuals with these conditions are also at increased risk for comorbidities including depression, substance use disorders, and cardiovascular disease, further complicating their clinical profile and necessitating more comprehensive treatment strategies.

Despite the availability of pharmacotherapy, such as selective serotonin reuptake inhibitors (SSRIs) and benzodiazepines, alongside cognitive-behavioral therapy (CBT), there remain substantial challenges in achieving and maintaining symptom relief. Response rates vary widely, and a significant proportion of patients experience partial or inadequate relief, with some exhibiting treatment-resistant symptoms. Moreover, pharmacological treatments can be associated with side effects like weight gain, fatigue, and cognitive impairment, which may lead to discontinuation or non-adherence. These limitations highlight a critical need for alternative or adjunctive interventions that can provide more effective, sustainable, and safer outcomes.

This trial was therefore designed to assess the prevalence of pathogenic gut bacteria among patients with anxiety, depression, and panic disorder compared to healthy controls.

Objective: This study aims to investigate the etiology of anxiety, depression, and panic disorders, providing new evidence and insights into the root causes, potentially offering a novel approach to these conditions..

Findings from this study are anticipated to advance clinical understanding and treatment options for anxiety, depression and panic disorders, providing a potentially more effective approach and that provide lasting relief for patients struggling with these conditions.

• Study Type: Observational
• Enrollment (Actual): 500

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Mississauga, Ontario, Canada, L5B3C2
      • MedBliss Research Network

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

The study population will consist of adult males and females aged 18 to 65 recruited from the general population and outpatient mental health clinics. Participants will include individuals with clinically confirmed anxiety, depression, or panic disorder, as well as healthy control subjects with no psychiatric history. The study will aim to include participants from diverse ethnic and cultural backgrounds to ensure broad representation of the population.

Description

Inclusion Criteria:

• • Adults aged 18-65 years.

  • Either of the following:

    1. Diagnosed with anxiety, depression, or panic disorder according to DSM-5 criteria, regardless of current treatment status.
    2. Healthy individuals with no history of psychiatric disorders (control group).
  • Able to provide informed consent and stool sample.

Exclusion Criteria:

• • Diagnosis of psychotic disorders or neurocognitive conditions.

  • Use of systemic antibiotics or antifungals within the past 60 days.

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Patients under ongoing treatment; Participants in this group are adults currently receiving ongoing treatment for anxiety, depression, or panic disorder. Treatment may include prescribed medication, psychotherapy, or other clinician-supervised care. These participants will complete the same baseline psychological assessments and stool microbiome testing as the other cohorts. Their data will help evaluate how existing treatments may influence gut microbiome composition and mental-health outcomes over time.	Diagnostic test: H pylori stool test; Participants will provide a stool sample for noninvasive testing to detect the presence of Helicobacter pylori bacteria. The test will be performed using a validated laboratory assay that identifies H. pylori antigens in stool. Results will be used to assess potential associations between H. pylori infection, gut microbiome composition, and symptoms of anxiety or depression. The test is diagnostic only and does not involve administration of any drug or treatment.; Diagnostic test: Bacterial stool analysis; Participants will provide stool samples for microbiome sequencing using a validated laboratory assay. The analysis will characterize bacterial taxa within the gut microbiome and identify potential pathogenic species. Sequencing results will be correlated with psychological assessments and clinical measures to investigate relationships between gut microbial composition and symptoms of anxiety, depression, and panic disorder.
Healthy controls with no psychiatric history; Participants in this group are healthy adults with no self-reported or clinically diagnosed history of psychiatric or neurological disorders. They will complete the same baseline assessments and biological sample collection (including stool microbiome testing) as the clinical cohort, but will not receive any treatment or individualized intervention. Their data will serve as a comparison reference to help identify microbiome and biomarker patterns associated with anxiety and depression.	Diagnostic test: H pylori stool test; Participants will provide a stool sample for noninvasive testing to detect the presence of Helicobacter pylori bacteria. The test will be performed using a validated laboratory assay that identifies H. pylori antigens in stool. Results will be used to assess potential associations between H. pylori infection, gut microbiome composition, and symptoms of anxiety or depression. The test is diagnostic only and does not involve administration of any drug or treatment.; Diagnostic test: Bacterial stool analysis; Participants will provide stool samples for microbiome sequencing using a validated laboratory assay. The analysis will characterize bacterial taxa within the gut microbiome and identify potential pathogenic species. Sequencing results will be correlated with psychological assessments and clinical measures to investigate relationships between gut microbial composition and symptoms of anxiety, depression, and panic disorder.
Patients with clinically confirmed anxiety, depression, and panic disorder.; Participants in this cohort are adults with a current, clinically confirmed diagnosis of anxiety disorder, depressive disorder, or panic disorder. Each participant will provide baseline psychological assessments and biological samples, including stool microbiome testing. Based on their results, they may receive individualized lifestyle or dietary recommendations under physician supervision. Participants will be followed over time to evaluate changes in mood, stress, and biological markers related to mental-health outcomes.	Diagnostic test: H pylori stool test; Participants will provide a stool sample for noninvasive testing to detect the presence of Helicobacter pylori bacteria. The test will be performed using a validated laboratory assay that identifies H. pylori antigens in stool. Results will be used to assess potential associations between H. pylori infection, gut microbiome composition, and symptoms of anxiety or depression. The test is diagnostic only and does not involve administration of any drug or treatment.; Diagnostic test: Bacterial stool analysis; Participants will provide stool samples for microbiome sequencing using a validated laboratory assay. The analysis will characterize bacterial taxa within the gut microbiome and identify potential pathogenic species. Sequencing results will be correlated with psychological assessments and clinical measures to investigate relationships between gut microbial composition and symptoms of anxiety, depression, and panic disorder.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Presence of pathogenic gut bacteria	The presence of pathogenic bacterial species will be identified through microbiome sequencing of stool samples using a validated laboratory assay. Sequencing data will be analyzed to detect and quantify bacterial taxa associated with dysbiosis and pathogenicity within the gut microbiome. The primary outcome will be defined as the detection of one or more bacterial pathogens meeting pre-specified taxonomic or functional criteria.	Day 10 Upon receipt of stool analysis results

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Symptom reduction, and eradication.	Changes in psychological symptom severity will be assessed using validated clinical instruments for anxiety, depression, and panic disorder. Composite symptom scores will be calculated and compared with baseline values to evaluate reductions in symptom severity over time. Correlations between the eradication of pathogenic gut bacteria and improvements in psychological symptoms will also be examined.	Day 0 (baseline), Day 24 (post-eradication reassessment), and Day 30 (post-eradication reassessment)

Collaborators and Investigators

• Sponsor: University of Toronto
• Collaborators: MedBliss Research Network

Study record dates

Study Major Dates

• Study Start (Actual): December 10, 2025
• Primary Completion (Actual): January 25, 2026
• Study Completion (Actual): February 10, 2026

Study Registration Dates

• First Submitted: November 18, 2025
• First Submitted That Met QC Criteria: December 5, 2025
• First Posted (Actual): December 8, 2025

Study Record Updates

• Last Update Posted (Actual): April 29, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Mental Disorders; Behavioral Symptoms; Behavior; Anxiety Disorders; Depression; Mood Disorders; Panic Disorder
• Other Study ID Numbers: Pro00084759

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 privacy considerations and data governance restrictions related to identifiable microbiome and psychological data. Summary results and aggregated findings will be made publicly available through publication and ClinicalTrials.gov reporting.

Drug and device information, study documents

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