ANZCTR - Registration

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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]

None

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Cognitive impairment

Condition category

Condition code

Neurological

Studies of the normal brain and nervous system

Neurological

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]

Behaviour

Intervention code [2]

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]

Corsi Blocks memory span

Timepoint [1]

Immediately before non-invasive brain stimulation (tDCS, tRNS or sham) and 10 minutes following brain stimulation onset across three experimental sessions.

Primary outcome [2]

Tower of London number of moves

Timepoint [2]

Immediately before non-invasive brain stimulation (tDCS, tRNS or sham) and 10 minutes following brain stimulation onset across three experimental sessions.

Secondary outcome [1]

Corsi Blocks reaction times.

Timepoint [1]

Immediately before non-invasive brain stimulation (tDCS, tRNS or sham) and 10 minutes following brain stimulation onset across three experimental sessions.

Secondary outcome [2]

Tower of London total time.

Timepoint [2]

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

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

Funding & Sponsors

Funding source category [1]

University

Name [1]

Murdoch University

Address [1]

90 South Street, Murdoch, 6150, WA.

Country [1]

Australia

Primary sponsor type

University

Name

Murdoch University

Address

90 South Street, Murdoch, 6150, WA.

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Murdoch University Human Research Ethics Committee

Ethics committee address [1]

90 South Street, Murdoch Western Australia 6150

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

Approval date [1]

24/03/2023

Ethics approval number [1]

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

Dr Luca Aquili

Address

Murdoch University
90 South Street,
Murdoch, 6150,
WA

Country

Australia

Phone

+61 89360 2348

Fax

[email protected]

Contact person for public queries

Name

Luca Aquili

Address

Murdoch University
90 South Street,
Murdoch, 6150,
WA

Country

Australia

Phone

+61 89360 2348

Fax

[email protected]

Contact person for scientific queries

Name

Luca Aquili

Address

Murdoch University
90 South Street,
Murdoch, 6150,
WA

Country

Australia

Phone

+61 89360 2348

Fax

[email protected]

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

No/undecided IPD sharing reason/comment

What supporting documents are/will be available?

Doc. No.	Type	Citation	Link	Email	Other Details	Attachment
18730	Ethical approval					385635-(Uploaded-28-03-2023-14-07-59)-Study-related document.pdf

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.

Trial Review

Documents added manually

Documents added automatically