Effect of Transcranial Direct Current Stimulation (tDCS) and Probiotic Supplementation in Overweight Adults

Study Overview
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Brief Summary
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The aim of the current study is to investigate and compare the effectiveness of probiotic supplementation and tDCS stimulation on risky decision-making related to food choices in overweight people. Considering the relatively established communication and interaction between the gut-brain-microbiome axis, the investigators expect that transcranial direct current stimulation and probiotic supplementation can both improve decision-making (decrease risky and impulsive decisions) and increase self-control in overweight people.

Official Title
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Comparing the Effectiveness of Transcranial Direct Stimulation (tDCS) and Probiotic Supplementation on Risky Decision-making, Impulsivity, Self-control, and Food Selection in Overweight Adults

Conditions
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Overweight and Obesity

Intervention / Treatment
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* Drug: Probiotic Blend Capsule
* Device: tDCS
* Device: Sham tDCS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI over 25 Higher than normal fat level Exclusion Criteria: Pregnancy Breastfeeding Smoking more than 10 cigarettes a day Excessive consumption of alcohol Suffering from chronic cardiovascular and kidney diseases Chronic digestive diseases such as celiac disease, Chronic inflammatory bowel diseases such as colitis, intestinal surgery, cancer, etc. Suffering from acute and chronic diarrhea in the last one month Taking antibiotics in two months before the start of the study, Continuous use of prebiotic and probiotic products and drugs in one month before the start of the intervention Frequent use of antibiotics during the last month before the start of the intervention Taking weight loss medications and following a special slimming diet in the last 3 months before the intervention. History of epilepsy and seizures, stroke, Use of pacemaker Presence of metal implanted in the scalp or brain, Presence of skin lesions at the tDCS stimulation site, and history of head injury or brain surgery. Brain disorders and long-term and chronic use of neuropsychiatric drugs.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Active tDCS over the dorsolateral prefrontal cortex (DLPFC)<br>In this group, participants will receive active 2 milliampere (mA) tdcs over the DLPFC (anode on F3 and cathode onF4) for 20 minutes. | Device: tDCS<br>* Using a tDCS device, a mild direct electric current is going to be non-invasively administered to the brain using rubber electrodes placed over the scalp.<br>|
| Active Comparator: Active tDCS over the ventromedial prefrontal cortex (VMPFC)<br>In this group, participants will receive active 2 mA tdcs over the VMPFC (anode on Fpz and cathode on Cz) for 20 minutes. | Device: tDCS<br>* Using a tDCS device, a mild direct electric current is going to be non-invasively administered to the brain using rubber electrodes placed over the scalp.<br>|
| Sham Comparator: Sham tDCS Stimulation<br>In this group, participants will receive sham tDCS which will ramp up for 30 s at the beginning of the session and then ramp down and be switched off during the 20-minute stimulation session. | Device: Sham tDCS<br>* Using a tDCS device, a mild direct electric current is going to be non-invasively administered to the brain using rubber electrodes placed over the scalp. At this arm the electric current will be applied for a very short time (30 s) after which the device will turn off, thus providing the initial tingling sensation over the scalp but not interfering with the ongoing brain activity.<br>|
| Active Comparator: Probiotic supplementation<br>In this group, participants will consume 2 probiotic supplements (The synbiotics family) daily, for one month. | Drug: Probiotic Blend Capsule<br>* By a probiotic blend capsule a specific product is intended which contains the following: Lactobacillus rhamnosus Lactobacillus plantarum Lactobacillus casei Lactobacillus helveticus Lactobacillus acidophilus Lactobacillus bulgaricus Lactobacillus gasseri Bifidobacterium bifidum Bifidobacterium lactis Bifidobacterium breve Bifidobacterium longum Streptococcus thermophile Fructooligosaccharides (FOS).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Body analysis test | This is a technique to determine the percentage of body mass that is fat compared to muscle. It can also indicate where the fat and muscle are carried within the body. | Depending on the experimental group: 10 stimulation days in tDCS groups and 30 days in the probiotic group. | 
| Impulsive Behavior Scale Questionnaire measuring Urgency, Premeditation (lack of), Perseverance (lack of), and Sensation seeking (UPPS) | This is a self-report tool that assesses five subscales (urgency, premeditation, perseverance, sensation seeking, and positive urgency) that are used to measure five distinct dimensions of impulsive behavior; each scale ranging from 4 to 16); Higher scores represent worse outcome. | Depending on the experimental group: 10 stimulation days in tDCS groups and 30 days in the probiotic group. | 
| Eating attitudes Test (EAT-26) | This tool is used to identify the presence of eating disorder risk based on attitudes, feelings and behaviours related to eating. The total score (between 0 and 78) provides an overall risk score, where higher scores indicating greater risk of an eating disorder. | Depending on the experimental group: 10 stimulation days in tDCS groups and 30 days in the probiotic group. | 
| Balloon analogue risk task (BART) | BART is a computerized decision-making task that is used to assess risk-taking behavior. The BART simulates a real-world situation, involving actual risky behavior, where taking a risk up until a certain point yields a reward. | Depending on the experimental group: 10 stimulation days in tDCS groups and 30 days in the probiotic group. | 
| Tangney self-control questionnaire (Form 36) | This is a self-report measurement to assess individual differences in traits of self-control. Scores range from 0 to 144 with higher scores representing worse outcome. | Depending on the experimental group: 10 stimulation days in tDCS groups and 30 days in the probiotic group. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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transcranial direct current stimulation, obesity, overweight, impulse control