Effect of Anodal Transcranial Direct Current Stimulation (tDCS) Over the Right-hemisphere on Picture Naming in Chronic Aphasia

Study Overview
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Brief Summary
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There are two opposing hypotheses, namely the interference and laterality-shift hypotheses, regarding the role of the right hemisphere (RH) in language recovery following a left hemisphere damage. Transcranial direct current stimulation (tDCS) has received increasing attention as a potential complement to behavioural therapy. This preliminary study aimed to examine the effect of excitatory (anodal) stimulation of right inferior frontal gyrus (IFG) on naming abilities of chronic people with aphasia (PWA) to examine the compensatory versus interference role of RH in language recovery, and to confirm the application of tDCS does not induce adverse effects on other cognitive and language functions.

Official Title
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The Effect of tDCS Stimulation of Right Inferior Frontal Gyrus on Language Recovery in Speakers With Aphasia

Conditions
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Aphasia

Intervention / Treatment
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* Device: tDCS stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: People with chronic aphasia following the stroke Exclusion Criteria: history of seizure or epilepsy, previous adverse reactions to TMS/tDCS, having a pace-maker or a metal implanted in the brain being pregnant

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

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: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: anodal tDCS<br>20 minutes of one mA anodal High-Definition tDCS (HD-tDCS) over right IFG combined with 40 minutes of naming therapy for five consecutive days in week 1 | Device: tDCS stimulation<br>* The study examines the effect of excitatory stimulation of right inferior frontal gyrus (IFG) on naming abilities of people with aphasia (PWA) as compared to sham stimulation to examine the compensatory versus interference role of right hemisphere in language recovery after stroke.<br>* Other names: language therapy;|
| Sham Comparator: sham tDCS<br>20-minutes sham HD-tDCS with 40-minutes therapy of naming therapy for five consecutive days in week 1 | Device: tDCS stimulation<br>* The study examines the effect of excitatory stimulation of right inferior frontal gyrus (IFG) on naming abilities of people with aphasia (PWA) as compared to sham stimulation to examine the compensatory versus interference role of right hemisphere in language recovery after stroke.<br>* Other names: language therapy;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Picture naming task | One hundred and sixty pictures of concrete nouns from the Snodgrass and Vanderwart (1980) picture set (colored version) were utilised to measure the percentage of object naming accuracy. In particular, these pictures were divided into Set A (training targets) and Set B (untrained generalization targets), with eighty stimuli in each set. | Immediately after the end of each treatment session and block | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| language task | * Overall language skills are measured through the overall aphasia scores provided by the Cantonese version of Western Aphasia Battery (short-form). The scale is called Aphasia quotient: Minimum value = 0, maximum value = 100, with higher scores mean a better performance. | Immediately after the end of each treatment block | 
| Cognitive task | The cognitive skills are measured through the subtest scores provided by Oxford Cognitive Screening-Cantonese. The test uses different sub-tests including the Picture naming, Semantics, Orientation, Visual field task, Sentence reading , Calculation, Attention, Praxis, Memory, and Executive tasks. The range of values varies across the subtests. For all subtests except the executive task, the higher scores reflect better performance. For executive tasks the lower scores reflect better performance. | Immediately after the end of each treatment block | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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tDCS, Aphasia, naming