Cognitive and Metabolic Effects of a Probiotic Supplement

Study Overview
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Brief Summary
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To examine the cognitive and metabolic effects of a probiotic supplement that is readily and already available for purchase in public drug stores. This study is a double-blinded randomized cross-over placebo-controlled intervention study. Participants will be randomized to receive either the probiotic supplement or the placebo during the first intervention period which will last 2 weeks. This will be followed by a washout period, after which they will proceed to the second intervention period, also lasting 2 weeks and also followed by a washout period.

Official Title
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Placebo-controlled Randomized Trial of Cognitive and Metabolic Effects of a Probiotic Supplement

Conditions
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Probiotics, Dietary Supplements, Metabolism, Food Preferences, Microbiota

Intervention / Treatment
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* Behavioral: Inhibitory task
* Procedure: Blood samples
* Biological: Feces collection
* Procedure: Caloric preload
* Behavioral: Food selection task
* Behavioral: Memory task
* Behavioral: Food consumption task


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male Age 18-28y Healthy (self-reported) and not on medication Non-smoking Normal sleep-wake rhythm (i.e. 7-8 h per night, self-reported via diaries) Regular meal patterns with daily breakfast Exclusion Criteria: Major illness Taking any serious medications Any sleep conditions (e.g. irregular bedtimes, sleep complaints) Any dietary issues with the food items provided Current or history of endocrine, neurological or psychiatric disorders Shift work in the preceding three months or for a long duration Time travel over a significant number of time zones in the preceding two months Too much weight gain or weight loss in the preceding three months Excessive intake of fermented dairy products Intake of probiotics Recent antibiotic treatment (last 6 months) Recent intake of certain dietary supplements Excessive caffeine (>5 cups daily) or alcohol intake (>2 alcohol units daily)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 28 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Probiotic<br>Probiotic pills given for 2 weeks, during one of the interventions that the participants is either randomized to as the first or second intervention period. At day 0 and following each intervention period (at week 2 and week 6), participants will be tested using Inhibitory task, Blood samples, Feces collection, Caloric preload, Food selection task, Memory task and Food consumption task. | Behavioral: Inhibitory task<br>* Participants perform a binary decision on each presented stimuli. Of the two possible outcomes, participants are instructed to make a motor response (go) for one type, and are to withhold a response (no-go) for the other type. Reaction time and accuracy are measured for each event<br>Procedure: Blood samples<br>* Hormone levels will be analyzed from blood samples obtained before and after a caloric preload given at each visit<br>Biological: Feces collection<br>* Feces samples will be collected on the morning of each visit, before and after each 2-week intervention period, as well as after each 2-week washout period following each intervention period.<br>Procedure: Caloric preload<br>* A caloric preload will be given to participants, following which blood will be taken at 65 minutes later (specified in Blood sampling) following the ingestion of the caloric preload.<br>Behavioral: Food selection task<br>* Participants are given the opportunity to write and use a computer program to specify amount and type of food would ideally like to consume<br>Behavioral: Memory task<br>* Participants perform short memory tasks on each visit<br>Behavioral: Food consumption task<br>* Participants are given a selection of food items to consume on each visit<br>|
| Placebo Comparator: Placebo<br>Placebo pills given for 2 weeks, during one of the interventions that the participants is either randomized to as the first or second intervention period. At day 0 and following each intervention period (at week 2 and week 6), participants will be tested using Inhibitory task, Blood samples, Feces collection, Caloric preload, Food selection task, Memory task and Food consumption task. | Behavioral: Inhibitory task<br>* Participants perform a binary decision on each presented stimuli. Of the two possible outcomes, participants are instructed to make a motor response (go) for one type, and are to withhold a response (no-go) for the other type. Reaction time and accuracy are measured for each event<br>Procedure: Blood samples<br>* Hormone levels will be analyzed from blood samples obtained before and after a caloric preload given at each visit<br>Biological: Feces collection<br>* Feces samples will be collected on the morning of each visit, before and after each 2-week intervention period, as well as after each 2-week washout period following each intervention period.<br>Procedure: Caloric preload<br>* A caloric preload will be given to participants, following which blood will be taken at 65 minutes later (specified in Blood sampling) following the ingestion of the caloric preload.<br>Behavioral: Food selection task<br>* Participants are given the opportunity to write and use a computer program to specify amount and type of food would ideally like to consume<br>Behavioral: Memory task<br>* Participants perform short memory tasks on each visit<br>Behavioral: Food consumption task<br>* Participants are given a selection of food items to consume on each visit<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Memory function | Memory test to examine the influence of probiotic supplement compared with placebo on memory function (declarative and working memory) | Change in memory function assessed at baseline (week 0), post-intervention 1 (at week 2), pre intervention 2 (week 6), post intervention 2 (week 8) and post-washout intervention 2 (week 12) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glycometabolic regulation | Glucose, insulin and other hormonal values during fasting and 1 hour following a standardized caloric preload | Change in glycometabolic regulation assessed at baseline (week 0), post-intervention 1 (at week 2), pre intervention 2 (week 6), post intervention 2 (week 8) and post-washout intervention 2 (week 12) | 
| Food preferences | Will test whether participants food preferences are changed following each intervention, as compared with before each intervention. Test will be written and computer-based. | Change in food preferences assessed at baseline (week 0), post-intervention 1 (at week 2), pre intervention 2 (week 6), post intervention 2 (week 8) and post-washout intervention 2 (week 12) | 
| Inhibitory task | Participants perform a binary decision on each presented stimuli. Of the two possible outcomes, participants are instructed to make a motor response (go) for one type, and are to withhold a response (no-go) for the other type. Reaction time and accuracy are measured for each event. | Change in inhibitory task performance assessed at baseline (week 0), post-intervention 1 (at week 2), pre intervention 2 (week 6), post intervention 2 (week 8) and post-washout intervention 2 (week 12) | 
| Food consumption task | Participants will be offered a food selection and their consumption will be measured. | Change in food consumption task assessed at baseline (week 0), post-intervention 1 (at week 2), pre intervention 2 (week 6), post intervention 2 (week 8) and post-washout intervention 2 (week 12) | 
| Sleep patterns |  | Change in sleep patterns as assessed at baseline (week 0), post-intervention 1 (at week 2), pre intervention 2 (week 6), post intervention 2 (week 8) and post-washout intervention 2 (week 12) | 
| Microbiome changes | Changes in microbiome will be assessed following treatment with either placebo or probiotics; feces will be collected according to standardized criteria. | Microbiome assessed at baseline (week 0), post-intervention 1 (at week 2), pre intervention 2 (week 6), post intervention 2 (week 8) and post-washout intervention 2 (week 12) |