Investigation of the Mechanisms of the Gut-brain Axis in Binge Eating and Obesity.

Official title

Gut2Brain: Investigation of the Mechanisms of the Gut-brain Axis in Binge Eating and Obesity

Overview

Binge Eating Disorder (BED) is a recently recognized eating disorder, characterized by recurrent episodes of overeating with a loss of control. Highly comorbid with obesity, BED is associated with poor outcomes in weight loss treatments and presents unique challenges due to its distinct neuro-psycho-biological mechanisms, which remain poorly understood. The Microbiota-Gut-Brain Axis (MGBA) is a bidirectional communication system linking the gut microbiota with the central nervous system, that plays a critical role in regulating appetite, mood, and eating behavior. Dysregulations in MGBA may contribute to the development and maintenance of BED, offering a novel framework for understanding its complex mechanisms and identifying new therapeutic targets. Psychobiotics -pre-, pro-, or symbiotics that modulate the microbiota- emerge as a promising treatment strategy to address BED symptoms by influencing MGBA activity. The goal of this randomized clinical trial (RCT) is to investigate the role of psychobiotics in modulating the gut-brain axis and improving binge eating in adults, with a particular focus on evaluating these effects independently of obesity status. This project stands out for its comprehensive approach to understanding BED, integrating psychological, neurofunctional, hormonal, and microbiota factors that contribute to this complex disorder. The main questions it aims to answer are: * What specific alterations in the MGBA pathways are associated with BED? * Can psychobiotic supplementation effectively reverse microbiota alterations and modulate MGBA activity, ultimately improving BED symptoms? Researchers will compare participants receiving psychobiotics to those receiving a look-alike substance that contains no drug (a placebo) to evaluate whether psychobiotics impact endocrine hormones, neurofunction, psychological and behavioral factors related to eating regulation, and BED symptoms. Participants will: * Undergo an assessment protocol that includes microbiota sampling, blood tests for hormone analysis, neurofunctional evaluations, and psychological/behavioral assessments before and after the psychobiotics/ placebo intervention. * Take psychobiotics or a placebo daily for 12 weeks and receive well-being monitoring * Participate in follow-up visits three months after the intervention to monitor changes in BED symptoms and related parameters.

Detailed description

This research project aims to investigate the role of psychobiotics in reversing MGBA alterations specific to BED. Therefore, a two-arm Randomized Clinical Trial (RCT) will be conducted. Participants will include individuals with BED and obesity, individuals with obesity only, and individuals with normal weight that will be randomly assigned to one of two groups:

i) an intervention group receiving psychobiotic supplementation ii) a control group receiving placebo supplementation. The sample size was computed considering the sample needed for 3 groups comparison in the RCT. G Power was used for (Mixed) ANOVAs considering f = 0.25, power = 90%, α = 0.05, and corr = 0.5., and 15% dropout.

At both the beginning and end of the trial, participants will undergo an assessment protocol.

Assessment protocol:

Participants will be invited to visit Braga Hospital where the assessment will take place for a scheduled appointment to undergo the assessment protocol for approximately 2 hours. The first step will involve the assessment of appetitive hormones through blood samples collected at three time points. The first blood sample (0 minutes) will be taken after a 12-hour overnight fast. Participants will consume 600 mL of a standardized liquid test meal, and additional blood draws will occur 10 and 30 minutes after the meal.

Between the second and third blood samples collected, participants will respond with some self-report measures. Specifically, self-report measures will assess socio-demographic data (age, sex, gender, education levels, marital status, and weight history) and psychological aspects: 1) emotional regulation and impulse control, distress tolerance, and positive and negative affects; 2) eating behavior, assessing eating expectancy, emotional eating, compulsive eating, and restraint eating. Then participants will do resting-state functional magnetic resonance imaging (rs-FMRI) performed to evaluate resting-state network connectivity.

Stool samples will be collected using a kit that includes all the necessary tools for proper sample collection and preparation for microbiota analysis.

The psychobiotic and the placebo package and instructions will be delivered during this scheduled appointment in Braga Hospital. All participants will be contacted weekly during the 12-week trial to ensure/increase adherence to the guidelines of prebiotic/placebo intervention.

Statistical Analyses:

Overall, multivariate analysis of variance (MANOVA) and/or general linear models (GLM) with mixed-model repeated measures will be used to examine group differences related to MGBA mechanisms, as well as significant main effects and interaction effects between baseline (T0) and the end of the RCT (T1). Structural equation modeling (SEM) will be employed to evaluate MGBA mechanisms as mediators of the changes observed between T0 and T1.

Interventions

• Dietary supplement Psychobiotic treatment
  The dietary supplementation will follow established guidelines, recommending an intake of 16 g of prebiotic per day, distributed across three meals, for a duration of 12 weeks.
• Other Placebo treatment
  The control group will receive identical packaging that matches the experimental treatment in taste and appearance and will follow the same guidelines for consuming the placebo. For ethical reasons, after the end of the RCT, the control group will be given the option to receive the same prebiotic supplement.

Primary outcome measures

• Gut Microbiota outcomes - Gut-Bacteria Composition [Time frame: Change measures: baseline and end of treatment at 12 weeks]
• Gut Microbiota outcomes - Molecules released by the gut-bacteria [Time frame: Change measures: baseline and end of treatment at 12 weeks]
• Psycho-behavioral outcomes - Three Factor Eating Questionnaire-21 [Time frame: Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.]
• Psycho-behavioral outcomes - Eating Expectancy Inventory [Time frame: Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.]
• Psycho-behavioral outcomes - Negative urgency subscale [Time frame: Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.]
• Psycho-behavioral outcomes - Difficulties in Emotion Regulation Scale [Time frame: Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.]
• Psycho-behavioral outcomes - Distress Tolerance Scale [Time frame: Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.]
• Neurofunctioning outcomes - Default mode network [Time frame: Change measures: baseline and end of treatment at 12 weeks]
• Neurofunctioning outcomes - Salience network [Time frame: Change measures: baseline and end of treatment at 12 weeks]
• Neurofunctioning outcomes - Meso/Paralimbic network [Time frame: Change measures: baseline and end of treatment at 12 weeks]

Secondary outcome measures (1)

• Eating Disorder Examination [Time frame: baseline moment]

Eligibility criteria

Inclusion criteria

• Portuguese adults (25 with normal weight; 25 with obesity only (30 ≤ BMI < 40) and BED; 54 with BED)
• Residents in Portugal for the past 10 years

Exclusion criteria

• Significant weight loss (>5% of body weight) in the past 2 years
• Antibiotic use in the past 6 months
• History of surgery or medical/psychiatric diseases
• Pregnant or breastfeeding
• History of drug use or dependence
• Use of medications that impact weight
• Have metal implants or pacemakers

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Double blind

Primary purpose

Treatment

Study locations

Portugal · 1 center

• Center for Psychology at University of Porto — Porto

Identifiers

NCT: NCT06823557 · UPorto_Gut2Brain

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗