tDCS Effects on GABA Concentration and Brain Functional Connectivity in Older Adults of Retirement Age

Study Overview
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Brief Summary
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The aim of this study is to investigate whether anodal tDCS over the left M1 leads to a decrease of GABA concentration and alterations of functional brain connectivity in older people, compared to sham tDCS.

Official Title
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Effects of Transcranial Direct Current Stimulation (tDCS) on GABA Concentration and Brain Functional Connectivity in Older Adults

Conditions
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Healthy Older Adults

Intervention / Treatment
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* Device: tDCS
* Device: sham-tDCS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: unobtrusive neuropsychological screening age: older adults of retirement age: ≥66 years Exclusion Criteria: Mild cognitive impairment (MCI) or other neurological diseases. History of severe alcoholism or use of drugs. Severe psychiatric disorders such as depression, psychosis (if not in remission) and severe untreated medical problems. Contraindication for MRI (claustrophobia, metallic implants, ferromagnetic metals in the body, disorders of thermoregulation, pregnant women).

Ages Eligible for Study
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Minimum Age: 66 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: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Anodal tDCS<br>Anodal stimulation during resting state fMRI | Device: tDCS<br> <br> |
| Experimental: Cathodal tDCS<br>Cathodal stimulation during resting state fMRI | Device: tDCS<br> <br> |
| Sham Comparator: Sham tDCS<br>Sham stimulation during resting state fMRI | Device: sham-tDCS<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| GABA concentration assessed by magnetic resonance spectroscopy (MRS) after anodal tDCS adjusted for baseline levels | Investigation whether anodal tDCS leads to a significant reduction of M1-GABA concentration in older adults compared to sham stimulation. | assessed immediately before and after a 15-min stimulation time | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| GABA concentration assessed by MRS before and after cathodal tDCS adjusted for baseline levels | To assess stimulation effects on GABA concentration by magnetic resonance spectroscopy are measured before and after cathodal tDCS. | assessed immediately before and after a 15-min stimulation time | 
| Resting-state functional connectivity changes | Functional connectivity as measured by resting-state fMRI during tDCS compared to sham | assessed during a 15-min stimulation time | 
| Genotyping of learning related polymorphisms | To assess predictors of positive reaction to brain stimulation, genotyping of several learning related polymorphisms will be performed | assessed during baseline screening | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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GABA concentration, tDCS