Trial Review

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Trial registered on ANZCTR


Registration number
ACTRN12623000351617
Ethics application status
Approved
Date submitted
28/03/2023
Date registered
5/04/2023
Date last updated
5/04/2023
Date data sharing statement initially provided
5/04/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
How does tyrosine intake influence brain stimulation effects on working memory and planning?
Scientific title
Interaction between tyrosine consumption, tDCS/tRNS and measures of planning and working memory performance in healthy participants.
Secondary ID [1] 309316 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Cognitive impairment 329598 0
Condition category
Condition code
Neurological 326449 326449 0 0
Studies of the normal brain and nervous system
Neurological 326450 326450 0 0
Other neurological disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
In this study, all participants will first complete a dietary screener questionnaire to capture average weekly tyrosine consumption.

Second, they will then complete two well-established neuropsychological measure of working memory known (Corsi Blocks) and planning (Tower of London). The tests will be administered in the lab using a piece of software called PEBL.

Third, they will undergo three different types of non-invasive brain stimulation: A) active transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (dlPFC) with the anode placed on the left and the cathode placed on the right hemisphere; B) active transcranial random noise stimulation (tRNS) with the electrodes placed in the same position as tDCS: C) sham/non-active stimulation.
The order of non-invasive brain stimulation allocation will be randomized for each participant. To avoid potential carryover effects of non-invasive brain stimulation, as this is a crossover design, each session will be separated by at least 72 hours.

For active tDCS, a current at 1.5 mA will be delivered for 10 minutes while the participant is relaxed plus the additional duration of the participant completing the Corsi Blocks and Tower of London test (approximately 10 minutes) with additional 30-second fade-in/fade-out periods.
For active tRNS, a digital high-pass filter is used to damp frequencies below 100 Hz, and deliver frequencies between 100 Hz to 640 Hz, with a maximum possible current set at 1.5 mA.
For sham, the stimulation will include only the initial 30-second ramp-up protocol to mimic active non-invasive brain stimulation and ramp down. Masking of the conditions will be achieved using the neuroConn study mode.

Testing will be carried out by three honours research students supervised by the PI and carried out in the Mind & Body lab at Murdoch University.
Intervention code [1] 325760 0
Behaviour
Intervention code [2] 325761 0
Treatment: Devices
Comparator / control treatment
For sham (control) stimulation, a current of 1.5 mA will be faded in over 30 seconds and then switched off. Double blinding will be achieved using the neuroConn study mode software and a different experimenter inputted a pre-assigned numerical code into the device to select the experimental condition (sham vs tDCS vs tRNS).
Control group
Placebo

Outcomes
Primary outcome [1] 334300 0
Corsi Blocks memory span
Timepoint [1] 334300 0
Immediately before non-invasive brain stimulation (tDCS, tRNS or sham) and 10 minutes following brain stimulation onset across three experimental sessions.
Primary outcome [2] 334301 0
Tower of London number of moves
Timepoint [2] 334301 0
Immediately before non-invasive brain stimulation (tDCS, tRNS or sham) and 10 minutes following brain stimulation onset across three experimental sessions.
Secondary outcome [1] 420191 0
Corsi Blocks reaction times.
Timepoint [1] 420191 0
Immediately before non-invasive brain stimulation (tDCS, tRNS or sham) and 10 minutes following brain stimulation onset across three experimental sessions.
Secondary outcome [2] 420192 0
Tower of London total time.
Timepoint [2] 420192 0
Immediately before non-invasive brain stimulation (tDCS, tRNS or sham) and 10 minutes following brain stimulation onset across three experimental sessions.

Eligibility
Key inclusion criteria
• You are aged between 18 and 50 years (the upper age limit of 50 years has been selected as there is some evidence that mild cognitive decline begins past this age)
• You are in good health
• You agree to fast 3 hours prior to testing (only water or herbal tea allowed) (glucose levels are known to modulate performance in several cognitive domains. By having all participants fast for 3 hours prior to testing, we can rule out an enhancing effect of glucose on the cognitive tasks).
Minimum age
18 Years
Maximum age
50 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
• Suffer from cardiac, hepatic, renal, and/or neurological disorders
• Have damaged or diseased skin on your face and scalp, or a sensitive scalp
• Have a history of alcohol or drug addiction, or severe psychiatric illness
• Are receiving drug treatment which may lower seizure threshold (i.e. epilepsy)
• Are pregnant
• Are sleep deprived (less than 6 hours a day)

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
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
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
17/04/2023
Actual
Date of last participant enrolment
Anticipated
21/08/2023
Actual
Date of last data collection
Anticipated
31/08/2023
Actual
Sample size
Target
30
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
WA

Funding & Sponsors
Funding source category [1] 313513 0
University
Name [1] 313513 0
Murdoch University
Country [1] 313513 0
Australia
Primary sponsor type
University
Name
Murdoch University
Address
90 South Street, Murdoch, 6150, WA.
Country
Australia
Secondary sponsor category [1] 315288 0
None
Name [1] 315288 0
Address [1] 315288 0
Country [1] 315288 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 312700 0
Murdoch University Human Research Ethics Committee
Ethics committee address [1] 312700 0
90 South Street, Murdoch Western Australia 6150
Ethics committee country [1] 312700 0
Australia
Date submitted for ethics approval [1] 312700 0
Approval date [1] 312700 0
24/03/2023
Ethics approval number [1] 312700 0
2023/029

Summary
Brief summary
Several studies have shown that the efficacy of non-invasive brain stimulation techniques such as tDCS and tRNS on cognitive function is partially modulated by individual characteristics. One of these characteristics is the amount of the neurotransmitter dopamine (DA) that a person has. Because some of the DA that is available in the human body is derived from our diet, one way of estimating DA availability is by using a food questionnaire which can tell us about someone’s tyrosine intake. Tyrosine is an amino acid that can be found in a variety of foods, and that through a chain of metabolizing steps eventually gets converted to DA. Thus, we hope to able to predict the effectiveness of tDCS/tRNS on planning and memory performance by an individual dietary consumption of tyrosine
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 125598 0
Dr Luca Aquili
Address 125598 0
Murdoch University
90 South Street,
Murdoch, 6150,
WA
Country 125598 0
Australia
Phone 125598 0
+61 89360 2348
Fax 125598 0
Email 125598 0
Luca.Aquili@murdoch.edu.au
Contact person for public queries
Name 125599 0
Dr Luca Aquili
Address 125599 0
Murdoch University
90 South Street,
Murdoch, 6150,
WA
Country 125599 0
Australia
Phone 125599 0
+61 89360 2348
Fax 125599 0
Email 125599 0
Luca.Aquili@murdoch.edu.au
Contact person for scientific queries
Name 125600 0
Dr Luca Aquili
Address 125600 0
Murdoch University
90 South Street,
Murdoch, 6150,
WA
Country 125600 0
Australia
Phone 125600 0
+61 89360 2348
Fax 125600 0
Email 125600 0
Luca.Aquili@murdoch.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
18730Ethical approval    385635-(Uploaded-28-03-2023-14-07-59)-Study-related document.pdf



Results publications and other study-related documents

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