Probiotics for Depressive Symptomatology and Neural Activity. (PRODAN)

The Acute and Chronic Effects of Ecologic® Barrier on Depressive Symptoms and Neural Activation.

This study aims to investigate the acute and chronic effects of 16-week probiotic supplementation (Ecologic® Barrier) on depressive symptoms and neural activity in those with mild-to-moderate depression.

Study Overview

• Status: Not yet recruiting
• Conditions: Mild-to-moderate Depression; Neural Activity; Executive Function (Cognition)
• Intervention / Treatment: Dietary supplement: Ecologic® Barrier; Dietary supplement: Placebo powder

Detailed Description

This study will use a randomised, double-blind, placebo-controlled design. A total of 76 participants will be recruited and will receive either one sachet of the probiotic (Ecologic® Barrier) or one sachet of a placebo, matched in taste, smell, appearance, and packaging. Outcomes will be measured at baseline, 24 hours, and at 16 weeks for all participants. These include measures of general mood, depressive symptoms, executive function, and neural activity. Neural activation will be measured using electroencephalography (EEG), specifically measuring the P300 event-related potential (ERP) during an n-back task. In addition to the n-back task, executive function, specifically working memory and cognitive flexibility will be tested using the task-switching task.

The main question this study aims to answer is:

• Does probiotic supplementation result in improvements in the primary outcome measure of vulnerability and sensitivity to depression, as well as secondary measures of rumination, hopelessness/suicidality, acceptance/coping, aggression, control, and risk aversion?
• Does probiotic supplementation improve accuracy and response times in executive function and working memory, measured by the Task Switching Task (TST) and n-back task?
• Is probiotic supplementation associated with an increased P300 amplitude and shorter P300 latency compared to baseline measures during the n-back task, in parietal and frontal lobe regions, with more pronounced effects in the 2-back task?
• Is probiotic supplementation associated with changes in alpha and theta band activity and symmetry, particularly after completing a demanding working-memory task?

• Study Type: Interventional
• Enrollment (Estimated): 76
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom, RG6 6UR
    • School of Psychology and Clinical Languages
    • Contact: Vanessa Sofia Amaral Lopes Simoes; Phone Number: 0118 987 5123; Email: v.amarallopessimoes@pgr.reading.ac.uk
    • Sub-Investigator: Vanessa Sofia Amaral Lopes Simoes

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Mild to moderate depression symptoms (BDI-II 12-28)
• Males and females
• Age range will be 25-40 years
• Right-handed participants only (required for EEG)

Exclusion Criteria:

• Taking antidepressants (up to 2 months prior to inclusion)
• Undergoing psychological treatment in the form of counselling, therapy or similar (up to 1 month prior to inclusion)
• Any diagnosed chronic medical condition (e.g. diabetes) or psychiatric illness.
• Use of antibiotics or laxatives (up to 3 months prior to inclusion)
• Use of probiotics and/or prebiotics (up to 1 month prior to inclusion)
• Enrolled in any other clinical trial (up to 1 month prior to inclusion)
• Following restrictive and/or unbalanced diets
• Smoking
• Continuous use of a weight-loss medication for more than one month prior to screening
• Significant gastrointestinal conditions affecting absorption, including but not limited to: inflammatory bowel disease; total colectomy or bariatric surgery; irritable bowel disease; end-stage renal disease; active cancer or cancer treatment within the past three years

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Ecologic® Barrier; Participants will consume one sachet of Ecologic® Barrier powder(1x10^10 CFU/day), mixed in warm water with a meal. The sachets can be stored at room temperature.	Dietary supplement: Ecologic® Barrier; Ecologic® Barrier (1x1010 CFU/day).; Other Names: Probiotics
Placebo Comparator: Placebo powder; A placebo matched for packaging, visual appearance, smell, and taste will be given. Similar to the instructions on how to take the probiotic, subjects will consume one sachet per day, kept at room temperature, mixed into warm water with a meal.	Dietary supplement: Placebo powder; Matched placebo; Other Names: placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Leiden Index of Depression Sensitivity - Revised (LEIDS-R) vulnerability/sensitivity for depression.	A standardised measure of cognitive reactivity. This questionnaire consists of 34 items, in which participants rate on a scale from 0 to 4, how strongly they feel each statement relates to them when they feel somewhat sad.	Baseline and 16 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Leiden Index of Depression Sensitivity - Revised (LEIDS-R). The following subscales are of interest: rumination, hopelessness/suicidality, acceptance/coping, aggression, control, and risk aversion.	A standardised measure of cognitive reactivity. This questionnaire consists of 34 items, in which participants rate on a scale from 0 to 4, how strongly they feel each statement relates to them when they feel somewhat sad.	Baseline, 24 hours, and 16 weeks
Beck Depression Inventory (BDI-II)	A robust tool consisting of 21 items used to measure the severity of depression. It focuses on symptoms experienced in the last 2 weeks, such as cognitive and affective symptoms.	Screening, baseline, 24 hours, and 16 weeks
Mini-International Neuropsychiatric Interview (MINI)	A short diagnostic interview designed to screen for 17 psychiatric disorders and the risk of suicide.	Baseline, 24 hours, and 16 weeks
Rumination Response Scale (RRS)	A self-report questionnaire measuring the tendency to focus on negative thinking, distressing symptoms, and their causes when people feel down, sad, or depressed.	Baseline, 24 hours, and 16 weeks
Neural Activity	P300 event-related potential (ERP) amplitude and latency during the n-back task. Resting-state and active-state alpha and theta power oscillations. An exploratory measure of the N2 ERP may be analysed alongside the P300.	baseline, 24 hours, and 16 weeks
Task-switching Task	This is a measure of executive function and sustained attention. Participants will be shown a circle with 8 equally spaced radii, 2 of which form a bold bisecting line. Numbers are chosen randomly from a set of 1-4 & 6-9 and displayed sequentially in a clockwise direction. A response of higher or lower than 5 is made for trials below the line, and a response of even or odd for numbers above the line. Accuracy and reaction time (RT) on correct trials, as well as accuracy and RT on trials where there is a 'switch cost' from stimuli moving from below to above the bold line and vice versa, are the main outcome measures.	Baseline, 24 hours, and 16 weeks
N-back task	This is an executive function and working memory task. There are varying difficulties of this task, but this trial will use the 0-back and 2-back versions. The 0-back task involves participants being shown a sequence of letters and having to respond when the current letter matches that of the previous letter. In the 2-back task, participants will have to respond when the current letter matches the letter from two trials ago.	baseline, 24 hours, and 16 weeks
Profile of Mood States short form (POMS-SF)	This is a condensed self-report questionnaire used to measure changes in mood, assessed across 6 sub-scales (tension-anxiety, depression-dejection, anger-hostility, vigour-activity, fatigue-inertia, and confusion-bewilderment) with 40 total items. A total mood disturbance score is provided.	Baseline, 24 hours, and 16 weeks
Visual Analogue Scale (VAS) of Positive and Negative feelings	Visual Analogue Scale of positive/negative feelings via a daily assessment. This includes two questions asking participants to rate on a scale from 0 to 100 the extent to which they felt positive or negative feelings.	Every day from baseline to the final 16-week time point.
Quality of Life (SF12)	The Quality of Life (SF12) is a questionnaire which asks for participants' views about their health. This information keeps track of how they feel and how well they can do their usual activities.	Baseline, 24 hours, and 16 weeks
Gastrointestinal Symptom Rating Scale (GSRS)	This is a 15-item self-reported questionnaire assessing the severity of gastrointestinal symptoms. It uses a 7-point Likert scale, covering five symptom domains: reflux, abdominal pain, indigestion, diarrhoea, and constipation symptoms.	Baseline, 24 hours, and 16 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Generalised Anxiety Disorder-7 (GAD-7)	This is a self-report questionnaire used to measure the severity of generalised anxiety disorder. It has seven items and asks individuals to rate the frequency of anxiety symptoms over the past two weeks, with scores ranging from 0 to 21 to determine anxiety levels. Baseline scores may be used as a covariate.	Baseline
Menstrual Cycle Data	Information regarding the first day of the most recent menstruation, regularity and contraception will be recorded. It is not a direct outcome measure, but data may be used as a covariate.	Baseline and 16 weeks
Epic-Norfolk Food Frequency Questionnaire (FFQ)	This is a validated tool for analysing the average habitual dietary intake of micro and macronutrients of an individual in the UK, which is particularly important to explore in order to understand how the probiotic supplement may interact with diet and gut microbiome diversity. Data will be processed using the FETA software.	Baseline and 16 weeks

Collaborators and Investigators

• Sponsor: University of Reading
• Collaborators: Winclove Probiotics B.V.

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): March 1, 2027

Study Registration Dates

• First Submitted: June 19, 2026
• First Submitted That Met QC Criteria: June 19, 2026
• First Posted (Actual): June 25, 2026

Study Record Updates

• Last Update Posted (Actual): June 25, 2026
• Last Update Submitted That Met QC Criteria: June 19, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Executive Function; Neural Activation; Probiotic Supplementation; Mild-to-moderate Depression
• Additional Relevant MeSH Terms: Dietary Supplements; Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Probiotics
• Other Study ID Numbers: UReading Probiotics Depression

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