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

The University of Hong Kong4 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Enrollment

Conditions

Aphasia

Interventions

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.

Eligibility

Sex: ALLMin age: 40 YearsMax age: 90 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

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.

Time frame: Immediately after the end of each treatment session and block

Secondary Outcomes

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.

Time frame: 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.

Time frame: Immediately after the end of each treatment block