Trial Review

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR


Registration number
ACTRN12623000649617
Ethics application status
Approved
Date submitted
12/01/2016
Date registered
15/06/2023
Date last updated
15/06/2023
Date data sharing statement initially provided
15/06/2023
Type of registration
Retrospectively registered

Titles & IDs
Public title
Can transcranial direct current stimulation enhance second language learning in healthy adults?
Scientific title
Can transcranial direct current stimulation enhance second language learning in healthy adults?
Secondary ID [1] 288288 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Second language learning 297250 0
Condition category
Condition code
Neurological 297454 297454 0 0
Studies of the normal brain and nervous system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This is a randomised double blind between subjects design.
The aims of the research project are to:
a. investigate the capacity of anodal transcranial direct current stimulation (tDCS) to Wernicke's area to improve the outcomes from a naturalistic second language learning program in healthy adults.

b. investigate the neurobiological correlates of tDCS induced second language learning.

tDCS involves the application of a very gentle electrical current applied using two surface electrodes (anode and cathode) to the scalp. Direct current will be administered via a purpose built battery-driven Eldith DC-stimulator (NeuroConn GmbH, Germany). Twenty minutes (including one-minute fade in/out) of 1mA anodal tDCS will be delivered via two 5cm x 7cm (total surface of 35 cm2) conductive rubber electrodes. Adhesion of the electrodes to the scalp and conductivity of the current to the scalp will be ensured by applying 10-twenty conductive gel between the head and electrode surface in accordance with manufacturer’s instructions. Stimulation over Wernicke’s area will be achieved by placing the anodal electrode at Cp5 (according to the 10-20 system). The cathode electrode will be placed over the lateral aspect of the contralateral orbit. Commonly reported adverse effects of tDCS are largely limited to transient mild tingling, itching and redness at the stimulation site.

Participants will be randomly allocated to receive either:
i) three active tDCS sessions whilst learning a second language over a 1 week period
ii) three sham tDCS whilst learning a second language over a 1 week period
(n = 20 in each group).

Language learning will be completed using the commercially available 'Elisabeth Smiths Learn Spanish Fast' language learning program. This is a 75-minute audio course that teaches 50 spanish words and expressions. The course is divided into three 25-minute sessions, tDCS will be provided in the manner stated above for the first 20 minutes of the each language learning sessions.

Participants will be visually monitored by the researcher for signs of engagement whilst completing the language learning task.
Intervention code [1] 293582 0
Other interventions
Comparator / control treatment
Stimulation will be delivered using the Eldith system which allows for
programming of tDCS and sham. Sham tDCS is achieved by switching off stimulation after approx. 30s; which occurs within the Eldith system allowing for administrator and patient blinding. There is no evidence that 30 seconds of tDCS induces any changes in the brain. The provision of stimulation for 30 seconds allows participants to experience the initial physical sensations of tDCS, which typically fade after 30seconds, thus providing a robust sham. This is a standard method of blinding for tDCS.
Control group
Placebo

Outcomes
Primary outcome [1] 297015 0
Behavioural: degree of proficiency gained from the language learning paradigm (i.e. number of phrases learnt) from the commercially available 'Elisabeth Smiths Learn Spanish Fast' language learning program. This is a 75-minute audio course teaches 50 spanish words and expressions.
Timepoint [1] 297015 0
At the third and final visit the number of Spanish phrases will be assessed prior to the EEG recording. This will be via a recall and recognition test designed by the researchers.
Secondary outcome [1] 319850 0
The first task is designed by the researcher and will present the foreign words included in the learning paradigm dispersed with words that are not included whilst EEG is being recorded. We’ll compare the P300 differences between these conditions before word learning and after word learning. We would expect that words that have been learned will show differences between baseline and post learning, with greater changes in the active tDCS group.ERP differences (P300) between the two groups
Timepoint [1] 319850 0
Baseline (at the first session prior to tDCS sessions) and Endpoint (at the third session, post tDCS sessions)
Secondary outcome [2] 319982 0
The second task is also developed by the researcher and will use a priming design to assess the creation of associations between words and meaning. Words will flash up on the screen very briefly, followed by an image. The participant will respond to an aspect of the meaning of the image. EEG is continuously recorded during this task. Participants will respond faster, and have a larger neural response if the priming word relates to the image, but only if they have learnt the association. We would predict that the active tDCS group will show a greater increase in the neural response compared to the sham stimulation group.
Timepoint [2] 319982 0
Endpoint (at the third session, post tDCS sessions)
Secondary outcome [3] 319983 0
We will also investigate resting state cortical connectivity, which will be examined by calculating EEG coherence and phase for all intrahemispheric and interhemispheric pairwise combinations of electrodes, across all frequency bands.
Timepoint [3] 319983 0
Baseline (at the first session prior to tDCS sessions) and Endpoint (at the third session, post tDCS sessions)

Eligibility
Key inclusion criteria
Inclusion Criteria
1. Are voluntary and competent to consent,
2. Are right handed,
3. Are between the ages of 18 and 45 years,
4. Are native English speakers
5. Have no history of neurological illness, mental illness or traumatic brain injury.
Minimum age
18 Years
Maximum age
45 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
General Exclusion Criteria
1. Are pregnant or lactating,
2. Currently taking any psychoactive medications,
3. Have metal anywhere in the head, except the mouth. This includes metallic objects such as screws, plates and clips from surgical procedures.
4. Have engaged in any second language learning as an adult.

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
This is a randomised double blind between subjects design. Participants will be randomly allocated to receive either active tDCS whilst learning a second language, or sham tDCS whilst learning a second language (i.e n = 20 in each group). Neither the participants nor the researchers directly involved in data collection will be aware of the tDCS group allocation.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Individuals will be randomized using a computer-generated list. As each new participant is enrolled they will be allocated to the next group as per a previously randomly generated list. Only the researcher conducting the randomisation (KH) will have access to the list.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
Intervention assignment
Parallel
Other design features
Phase
Type of endpoint/s
Statistical methods / analysis
The primary outcome measures will be behavioural, i.e. the degree of proficiency gained from the language learning paradigm (as index by the number of phrases learnt), accuracy and reaction time outcomes on the EEG language association tasks. We will also be analysing the P300 differences between groups for the EEG tasks. As no prior studies have measured electrophysiological outcomes associated with tDCS and language learning, information to base a formal power calculation in unavailable. However, multiple studies investigating tDCS have found group differences in cognitive performance and EEG activity with groups of this size or smaller (Hoy et al, 2013; Wirth et al., 2011).

All statistical analysis will be conducted using SPSS Version 20. Repeated measures of analysis of variance (ANOVA) will be used to compare the change in behavioural and EEG measures between the two groups (i.e. active tDCS and language learning, sham tDCS and language learning). Post hoc analysis will be conducted to tease out any main effects.

Recruitment
Recruitment status
Stopped early
Data analysis
No data analysis planned
Reason for early stopping/withdrawal
Lack of funding/staff/facilities
Date of first participant enrolment
Anticipated
Actual
12/05/2015
Date of last participant enrolment
Anticipated
Actual
31/10/2015
Date of last data collection
Anticipated
Actual
27/11/2015
Sample size
Target
40
Accrual to date
Final
24
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 292665 0
University
Name [1] 292665 0
Monash University
Country [1] 292665 0
Australia
Primary sponsor type
Individual
Name
A/ Prof Kate Hoy
Address
Monash Alfred Psychiatry research centre,
Level 4, 607 St Kilda Road,
Melbourne,
3004,
VIC
Country
Australia
Secondary sponsor category [1] 291386 0
None
Name [1] 291386 0
None
Address [1] 291386 0
None
Country [1] 291386 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 294137 0
Alfred Health Ethics Committee
Ethics committee address [1] 294137 0
Ground Floor, Linay Pavilion, The Alfred Hospital, 55 Commercial Rd, Melbourne VIC 3004
Ethics committee country [1] 294137 0
Australia
Date submitted for ethics approval [1] 294137 0
Approval date [1] 294137 0
19/01/2015
Ethics approval number [1] 294137 0
529/14

Summary
Brief summary
There are many studies that have shown that mild electrical stimulation delivered to the surface of the brain can improve a range of thinking skills, including learning, memory, decision-making and mathematical ability. This brain stimulation technique is called transcranial direct current stimulation (tDCS). There has been a lot of excitement about tDCS and its ability to improve peoples thinking skills, particularly their learning ability, however these improvements have largely been shown only in 'experimental' settings where improvements are seen on computerised tests in a laboratory. It is unclear whether these effects will translate to more 'real world' learning situations.

One of the most common examples of novel skill acquisition in adults is that of second language learning. Research has shown that second language learning in adults is facilitated by changes in brain activity in language related brain regions, i.e. Broca's (language production) and Wernicke's (language processing) areas. Previous research has shown that tDCS to such Wernicke’s area is able to induce faster and more accurate learning in an experimental language learning paradigm, where participants were required to learn the 'meaning' of psuedowords (i.e. /glump/). While these results are promising, it remains unclear as to whether they will translate in a meaningful way to 'real world' language learning. In addition, there has been very little research looking at the neurobiological correlates of tDCS enhanced learning in healthy populations and none in naturalistic learning.

In light of the above, the aims of the proposed research project are to:

a. investigate the capacity of tDCS to Wernicke's area to improve the outcomes from a naturalistic second language learning program in healthy adults.

b. investigate the neurobiological correlates of tDCS induced second language learning.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 62650 0
A/Prof Kate Hoy
Address 62650 0
Monash Alfred Psychiatry research centre, Level 4, 607 St Kilda Road, Melbourne, 3004 VIC
Country 62650 0
Australia
Phone 62650 0
+613 9076 5034
Fax 62650 0
Email 62650 0
[email protected]
Contact person for public queries
Name 62651 0
A/Prof Kate Hoy
Address 62651 0
Monash Alfred Psychiatry research centre, Level 4, 607 St Kilda Road, Melbourne, 3004 VIC
Country 62651 0
Australia
Phone 62651 0
+613 9076 5034
Fax 62651 0
Email 62651 0
[email protected]
Contact person for scientific queries
Name 62652 0
A/Prof Kate Hoy
Address 62652 0
Monash Alfred Psychiatry research centre, Level 4, 607 St Kilda Road, Melbourne, 3004 VIC
Country 62652 0
Australia
Phone 62652 0
+613 9076 5034
Fax 62652 0
Email 62652 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
We do not ethics approval to share data. We now include data sharing in ethics and PICF as a matter of course, but did not do that here. Therefore we do not have the consent of participants to share any data beyond the research team.


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.