The Effects of Transcranial Direct Current Stimulation on Executive Function in People With Mild to Moderate Dementia

Study Overview
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Brief Summary
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To study the effects of transcranial direct current stimulation on executive function in people with mild to moderate dementia

Detailed Description
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Extensive research had shown executive dysfunction in people with dementia (PWD) is associated with functional abnormalities in prefrontal regions such as the right inferior frontal gyrus (Right IFG) or the left dorsal lateral pre-frontal cortex (Left DLPFC) . Clinical studies suggest that tDCS may be a useful therapeutic tool. Post-tDCS improvements have also been shown in visuo-motor coordination of healthy controls and performance in working memory. The aim of this study is to investigate the effect of tDCS stimulation over left DLPFC or right IFG on attention, inhibition and working memory and their neural correlates in people with dementia (PWD) and healthy controls (HC).This study is planned as a double-blinded, randomized case-control interventional study with a duration of 30 months.

Official Title
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The Effects of Transcranial Direct Current Stimulation on Executive Function in People With Mild to Moderate Dementia

Conditions
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Dementia, Executive Function, Transcranial Direct Current Stimulation

Intervention / Treatment
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* Device: transcranial direct current stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: PWD must be aged at least 65 years or above when informed consent is obtained in the presence of his / her first degree relatives. PWD must meet criteria of DSM-V for dementia as well as for historical diagnosis of dementia. PWD must have a Chinese MoCA score > 19 (mild to moderate cognitive deficits) at screening. Subjects (both PWD and HC) must be physically healthy, and must be able to understand and be willing to sign the informed consent document Exclusion Criteria: Subject with major neurological illness. Subject with other diagnosed psychiatric disorders Subjects reported with history of substance abuse, which including alcohol, drugs or any medication which is indicative of chronic abuse. Failures to comply with the study protocol or to follow the instructions. Self-reported with known skin diseases or skin allergy history. Self-reported with metallic implants, dentures Self-reported with history of claustrophobia. (This is excluded because subject needs to stay in a quiet room with the head-mounted fNIRS and tDCS, which may elicit their feeling of anxiety)

Ages Eligible for Study
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Minimum Age: 65 Years
Maximum Age: 90 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
Interventional Model Description: double-blinded, randomized case-control interventional study
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: People with Dementia<br>Twenty subjects each group will be randomized to receive either anodal tDCS or shame tDCS over the Right iFG or Left DLPFC. A 2mA direct current for active tDCS (current density : .057 mA/cm2) with a 20 mins stimulation period | Device: transcranial direct current stimulation<br>* Each subject will undergo one tDCS stimulation session lasting for 20 minutes. A constant current of 2 mA will be applied with a linear fade in, fade out of 10 seconds to prevent electrical transients.<br>|
| Sham Comparator: Health Control<br>Twenty subjects each group will be randomized to receive either anodal tDCS or shame tDCS over the Right iFG or Left DLPFC. After a fade in period of 10s to mimic initial tDCS peripheral skin sensations, the stimulator will be turned off in order to prevent the induction of any neuromodulatory effect. | Device: transcranial direct current stimulation<br>* Each subject will undergo one tDCS stimulation session lasting for 20 minutes. A constant current of 2 mA will be applied with a linear fade in, fade out of 10 seconds to prevent electrical transients.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Haemodynamic changes | Change in hemodynamic level in two region of interest of prefrontal cortical regions, that is DLPFC and IFG | baseline and 5 minutes after tDCS | 
| Trail Making Test | change in Trail Making Test | baseline and 5 minutes after tDCS | 
| Behavior change | Change in the Chinese Multiple Errands Test | baseline and 5 minutes after tDCS | 
| N-back task | Change in N-back task | baseline and 5 minutes after tDCS | 
| Stop-signal task | Change in Stop-signal task | baseline and 5 minutes after tDCS |