Cognitive Behavioral Therapy for Functional Dyspepsia (Epigastric Pain Syndrome and Postprandial Distress Syndrome Subtypes)

Multimodal Phenotyping of Functional Dyspepsia: Controlled Trial on Response to Cognitive-Behavioral Therapy in Subtypes of Epigastric Pain Syndrome and Postprandial Discomfort Syndrome

The goal of this clinical trial is to learn whether adding Cognitive Behavioral Therapy (CBT) to standard medical treatment can improve symptoms in adults with Functional Dyspepsia. The study includes adults aged 18 to 65 years diagnosed with Functional Dyspepsia, classified as Epigastric Pain Syndrome or Postprandial Distress Syndrome.

The main questions it aims to answer are:

Does Cognitive Behavioral Therapy added to standard treatment reduce gastrointestinal symptoms compared with standard treatment alone? Do patients with Postprandial Distress Syndrome and Epigastric Pain Syndrome respond differently to Cognitive Behavioral Therapy? Researchers will compare optimized standard medical treatment alone to optimized standard treatment combined with Cognitive Behavioral Therapy to see if the addition of CBT leads to greater symptom improvement and better quality of life.

Participants will:

Be randomly assigned to receive either standard medical treatment alone or standard treatment plus Cognitive Behavioral Therapy Take part in clinical visits and complete questionnaires about gastrointestinal symptoms, psychological well-being, and quality of life Provide blood, saliva, and stool samples at several time points over a 12-month follow-up period

Functional Dyspepsia is a chronic disorder of gut-brain interaction characterized by persistent upper gastrointestinal symptoms in the absence of structural disease. It is commonly classified into Epigastric Pain Syndrome and Postprandial Distress Syndrome, which may reflect partially distinct underlying mechanisms. Standard medical treatments often provide incomplete symptom relief, and growing evidence supports a role for psychological factors and gut-brain axis dysregulation in symptom generation and persistence.

This randomized controlled trial investigates the effectiveness of adding a manualized Cognitive Behavioral Therapy program to optimized standard medical treatment in adults with Functional Dyspepsia. Participants are stratified by dyspepsia subtype and randomly assigned in a 1:1 ratio to receive either optimized standard treatment alone or optimized standard treatment combined with Cognitive Behavioral Therapy. Outcome assessors are blinded to treatment allocation.

The Cognitive Behavioral Therapy intervention is delivered individually by trained therapists and focuses on psychoeducation, cognitive restructuring, stress management, coping strategies, and behavioral and interoceptive exposure. The intervention is designed to target symptom-related cognitions, emotional responses, and behavioral patterns that may contribute to symptom persistence.

In addition to evaluating clinical efficacy, the study adopts a multimodal approach to characterize biological, psychological, and clinical factors associated with treatment response. Data collection includes clinical and psychological assessments and the collection of biological samples to explore markers related to inflammation, stress regulation, gut barrier function, and gut microbiota composition and activity. Measurements are obtained at baseline and during follow-up to assess changes over time and their relationship with symptom improvement.

The study aims to identify predictors of response to Cognitive Behavioral Therapy and to explore differences between Epigastric Pain Syndrome and Postprandial Distress Syndrome. By integrating clinical, psychological, and biological data, the trial seeks to support a more personalized treatment approach for Functional Dyspepsia and to improve the targeting of psychological interventions in clinical practice.

Inclusion Criteria:

• Age 18-65 years
• Diagnosis of Functional Dyspepsia according to Rome IV criteria
• Classification as Epigastric Pain Syndrome (EPS) or Postprandial Distress Syndrome (PDS)
• Active symptoms within the last month
• Willingness to participate in Cognitive Behavioral Therapy and provide biological samples for research
• Ability to provide written informed consent

Exclusion Criteria:

• Presence of structural gastrointestinal disease (e.g., peptic ulcer, malignancy)
• History of major abdominal surgery affecting the stomach or small intestine
• Severe psychiatric disorders (e.g., psychosis, bipolar disorder) interfering with participation
• Current participation in other interventional clinical trials
• Use of medications that may confound study outcomes (e.g., chronic corticosteroids, immunosuppressants)
• Pregnancy or breastfeeding