The Effect of Non-invasive Brian Stimulation on Language Production in Healthy Older Adults

Study Overview
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Brief Summary
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The use of non-invasive brain stimulation techniques like transcranial direct-current stimulation (tDCS) for rehabilitation of language is a growing field that needs further studies to determine how best it can be used to enhance treatment outcomes. It has been shown that tDCS can improve language performance in healthy and brain-injured individuals such as increased naming accuracy. However, at present, it is not known what effect tDCS has on higher-level language skills like discourse production (i.e. story telling, giving instructions) in healthy, older speakers. Therefore, the aim of this study is to investigate in healthy older adults, the effect of tDCS on discourse production as well as the ideal tDCS electrode placement for improving language at the discourse level. It is hypothesised that tDCS will result in greater language changes and improvements during discourse production compared to no stimulation.

Official Title
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The Effect of Transcranial Direct-current Stimulation on Discourse Production in Healthy Older Adults

Conditions
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Language Disorders, Aphasia, Stroke

Intervention / Treatment
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* Device: Transcranial direct-current stimulation (tDCS)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: At least 65 years of age Native English speakers Right handed Normal aided or unaided visual acuity At least secondary school level of education Exclusion Criteria: History of neurological disease or cognitive impairment Any contraindication of tDCS (i.e. history of seizures, metal implants)

Ages Eligible for Study
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Minimum Age: 65 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 on the left inferior frontal gyrus (IFG)<br> | Device: Transcranial direct-current stimulation (tDCS)<br>* Transcranial direct-current stimulation is a non-invasive brain stimulation method that can modify spontaneous cortical activity in targeted brain regions. Anodal tDCS delivered through a positively charged electrode has been found to increase cortical excitability in a targeted brain region. Application of tDCS has been found to improve language production in healthy and brain-injured speakers.<br>|
| Experimental: anodal tDCS on the right IFG<br> | Device: Transcranial direct-current stimulation (tDCS)<br>* Transcranial direct-current stimulation is a non-invasive brain stimulation method that can modify spontaneous cortical activity in targeted brain regions. Anodal tDCS delivered through a positively charged electrode has been found to increase cortical excitability in a targeted brain region. Application of tDCS has been found to improve language production in healthy and brain-injured speakers.<br>|
| Sham Comparator: sham tDCS<br> | Device: Transcranial direct-current stimulation (tDCS)<br>* Transcranial direct-current stimulation is a non-invasive brain stimulation method that can modify spontaneous cortical activity in targeted brain regions. Anodal tDCS delivered through a positively charged electrode has been found to increase cortical excitability in a targeted brain region. Application of tDCS has been found to improve language production in healthy and brain-injured speakers.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in word total | total number of words in a language sample | pre-intervention and immediately after the intervention | 
| Change in verb total | total number of verbs in a language sample | pre-intervention and immediately after the intervention | 
| Change in utterance total | total number of utterances (complete sentences including a predicate and argument) in a language sample | pre-intervention and immediately after the intervention | 
| Change in percent of Correct Information Units | The percent of accurately produced words that provide information relevant to the language task | pre-intervention and immediately after the intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hospital Anxiety and Depression Scale (HADS) | HADS is a 14-item scale which assesses non-somatic anxiety and depression symptoms experienced in the past week. Scores range from 0 to 21 for each sub-scale with a score ≥8 proposed for the identification of caseness, for both depression and anxiety. | 7 days | 
| EPIC Physical Activity Questionnaire (EPAQ2) | The EPAQ2 is a self completed questionnaire which collects information on a person's physical activity levels at home, work and recreation. Based on total activity hours in the last 12 months, the physical activity index categorises levels of physical activity into 'active', 'moderately inactive', 'moderately active' or 'active'. | 12 months | 
| The Keele Assessment of Participation (KAP) | The KAP is a short questionnaire that measures participation levels in various activities such as activities of daily living, social activities and work in the last 4 weeks. A score of 0 indicates no restriction in participation whereas scores from 1-11 indicate a restriction in participation in at least one activity ( the higher the score the greater the restriction). | 4 weeks |