Cognitive FlexibilityNCT03462303
Modulation of Cognitive Flexibility by Tyrosine Depletion and Transcranial Direct Current Stimulation
A study testing Anodal tDCS and tyrosine depleted drink and Anodal tDCS and balanced drink in people with Cognitive Flexibility, run by Sheffield Hallam University at 1 site in United Kingdom.
Trial summary
The dorsolateral prefrontal cortex (dlPFC) and dopamine (DA) have been implicated in the control of cognitive flexibility. However, while a great deal of what it is know regarding a causative relationship between cognitive flexibility and its neuronal underpinning comes from animal studies, human data have largely… Read more about this study
- Who is it for?
- Ages 18 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Cognitive Flexibility
- What is being tested?
- Anodal tDCS and tyrosine depleted drink and Anodal tDCS and balanced drink
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 36 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 12 Feb 2018to 30 Jun 2018
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Either male or female
- You are aged between 18 and 30 years
- You are in good health
- You agree to fast overnight prior to testing
Who cannot join
- Are suffering from cardiac, hepatic, renal, or neurological disorders
- Damaged or diseased skin on your face and scalp, or a sensitive scalp
- A history of alcohol or drug addiction, or severe psychiatric illness
- Are in drug treatment which may lower seizure threshold (i.e. epilepsy)
- You are pregnant
- Slept less than 6 hours prior to coming to the lab
Show all 11Show fewer
- Suffer from phenylketonuria
- A history of or current experience of migraine or headaches
- A history of or current use of antidepressants
- A history of or current use of tyrosine supplements
- Consume more than five beverages containing caffeine per day
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
Department of Psychology labs
Sheffield, South Yorkshire, S10 2BQ
About this study
The dorsolateral prefrontal cortex (dlPFC) and dopamine (DA) have been implicated in the control of cognitive flexibility. However, while a great deal of what it is know regarding a causative relationship between cognitive flexibility and its neuronal underpinning comes from animal studies, human data have largely been correlational (i.e. imaging investigations). In a recent study, the current research group examined whether putative increases in dopamine levels through tyrosine administration and blockage of these by cathodal (i.e. inhibitory) transcranial direct current stimulation (tDCS) of the dlPFC could be causally related to cognitive flexibility as measured by task switching and reversal learning.
The next step involves finding a way of lowering dopamine concentrations while anodal (i.e. excitatory) stimulation of the dlPFC is applied and cognitive flexibility measured. One experimental approach to reduce global DA synthesis and transmission is through acute phenylalanine and tyrosine depletion (APTD). This dietary intervention involves the administration of an amino-acid mixture lacking in tyrosine and phenylalanine, which can be used to selectively lower DA synthesis in humans.
- Conditions
- Cognitive Flexibility
- Being tested
- Sham tDCS and tyrosine depleted drink, Anodal tDCS and tyrosine depleted drink, Sham tDCS and balanced drink, Anodal tDCS and balanced drink
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Sham tDCS and tyrosine depleted drinkCombination product
Transcranial direct current stimulation (sham) of the dlPFC in combination with a tyrosine and phenylalanine free product.
Anodal tDCS and tyrosine depleted drinkCombination product
Transcranial direct current stimulation (anodal) of the dlPFC in combination with a tyrosine and phenylalanine free product.
Sham tDCS and balanced drinkCombination product
Transcranial direct current stimulation (sham) of the dlPFC in combination with a drink containing both tyrosine and phenylalanine.
Anodal tDCS and balanced drinkCombination product
Transcranial direct current stimulation (anodal) of the dlPFC in combination with a drink containing both tyrosine and phenylalanine.
| Study group | Role | What they receive |
|---|---|---|
| tDCS sham + balanced drink | Placebo comparator | Not described Receives: Combination Product: Sham tDCS and balanced drink |
| tDCS sham + tyrosine depleted drink | Experimental | Not described Receives: Combination Product: Sham tDCS and tyrosine depleted drink |
| tDCS anodal + balanced drink | Experimental | Not described Receives: Combination Product: Anodal tDCS and balanced drink |
| tDCS anodal +tyrosine depleted drink | Experimental | Not described Receives: Combination Product: Anodal tDCS and tyrosine depleted drink |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in cognitive flexibility performance
Measured using Wisconsin Card Sorting Test
Measured: Measured over 5 hours four times.1st measurement taken at baseline (i.e. time 0). 2nd measurement taken 120 minutes after measurement 1. 3rd measurement taken 220 minutes after measurement 1. 4th measurement taken 270 minutes after measurement 1.
Change in cognitive flexibility performance
Measured using Probabilistic Reversal Learning
Measured: Measured over 5 hours. 1st measurement taken at baseline (i.e. time 0). 2nd measurement taken 120 minutes after measurement 1. 3rd measurement taken 220 minutes after measurement 1. 4th measurement taken 270 minutes after measurement 1.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Mar 2018
- Study start12 Feb 2018
- Primary completion30 Jun 2018
- Study completion30 Jun 2018
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cognitive FlexibilityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Factorial
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 36 participants (actual)
Sponsor and investigators
- Lead sponsor
- Sheffield Hallam University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03462303
- Sponsor's protocol ID
- SheffieldHallamAquili2018
- Status last verified
- Sep 2018
- First submitted
- 20 Feb 2018
- Last updated
- 11 Sep 2018
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 11 Sep 2018. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Modulation of Cognitive Flexibility by Tyrosine Depletion and Transcranial Direct Current Stimulation
- ClinicalTrials.gov ID
- NCT03462303
- Acronym / sponsor ID
- SheffieldHallamAquili2018
- Conditions
- Cognitive Flexibility
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 36 participants (actual)
- Lead sponsor
- Sheffield Hallam UniversityUniversity, hospital or other
- Study start
- 12 Feb 2018 (actual)
- Primary completion
- 30 Jun 2018 (actual)
- Study completion
- 30 Jun 2018 (actual)
- First posted
- 12 Mar 2018 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The dorsolateral prefrontal cortex (dlPFC) and dopamine (DA) have been implicated in the control of cognitive flexibility. However, while a great deal of what it is know regarding a causative relationship between cognitive flexibility and its neuronal underpinning comes from animal studies, human data have largely been correlational (i.e. imaging investigations). In a recent study, the current research group examined whether putative increases in dopamine levels through tyrosine administration and blockage of these by cathodal (i.e. inhibitory) transcranial direct current stimulation (tDCS) of the dlPFC could be causally related to cognitive flexibility as measured by task switching and reversal learning.
The next step involves finding a way of lowering dopamine concentrations while anodal (i.e. excitatory) stimulation of the dlPFC is applied and cognitive flexibility measured. One experimental approach to reduce global DA synthesis and transmission is through acute phenylalanine and tyrosine depletion (APTD). This dietary intervention involves the administration of an amino-acid mixture lacking in tyrosine and phenylalanine, which can be used to selectively lower DA synthesis in humans.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Factorial
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| tDCS sham + balanced drink | Placebo comparator | Combination Product: Sham tDCS and balanced drink |
| tDCS sham + tyrosine depleted drink | Experimental | Combination Product: Sham tDCS and tyrosine depleted drink |
| tDCS anodal + balanced drink | Experimental | Combination Product: Anodal tDCS and balanced drink |
| tDCS anodal +tyrosine depleted drink | Experimental | Combination Product: Anodal tDCS and tyrosine depleted drink |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Either male or female
- You are aged between 18 and 30 years
- You are in good health
- You agree to fast overnight prior to testing
Key exclusion criteria (11 listed)
- Are suffering from cardiac, hepatic, renal, or neurological disorders
- Damaged or diseased skin on your face and scalp, or a sensitive scalp
- A history of alcohol or drug addiction, or severe psychiatric illness
- Are in drug treatment which may lower seizure threshold (i.e. epilepsy)
- You are pregnant
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Sham tDCS and tyrosine depleted drinkTranscranial direct current stimulation (sham) of the dlPFC in combination with a tyrosine and phenylalanine free product. | Combination product | tDCS sham + tyrosine depleted drink |
| Anodal tDCS and tyrosine depleted drinkTranscranial direct current stimulation (anodal) of the dlPFC in combination with a tyrosine and phenylalanine free product. | Combination product | tDCS anodal +tyrosine depleted drink |
| Sham tDCS and balanced drinkTranscranial direct current stimulation (sham) of the dlPFC in combination with a drink containing both tyrosine and phenylalanine. | Combination product | tDCS sham + balanced drink |
| Anodal tDCS and balanced drinkTranscranial direct current stimulation (anodal) of the dlPFC in combination with a drink containing both tyrosine and phenylalanine. | Combination product | tDCS anodal + balanced drink |
Primary outcome
Change in cognitive flexibility performance
Time frame: Measured over 5 hours four times.1st measurement taken at baseline (i.e. time 0). 2nd measurement taken 120 minutes after measurement 1. 3rd measurement taken 220 minutes after measurement 1. 4th measurement taken 270 minutes after measurement 1.
Measured using Wisconsin Card Sorting Test
Change in cognitive flexibility performance
Time frame: Measured over 5 hours. 1st measurement taken at baseline (i.e. time 0). 2nd measurement taken 120 minutes after measurement 1. 3rd measurement taken 220 minutes after measurement 1. 4th measurement taken 270 minutes after measurement 1.
Measured using Probabilistic Reversal Learning
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Sep 2018.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Anodal tDCS and tyrosine depleted drink and Anodal tDCS and balanced drink in people with Cognitive Flexibility, run by Sheffield Hallam University at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 11 Sep 2018. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in cognitive flexibility performance (time frame: Measured over 5 hours four times.1st measurement taken at baseline (i.e. time 0). 2nd measurement taken 120 minutes after measurement 1. 3rd measurement taken 220 minutes after measurement 1. 4th measurement taken 270 minutes after measurement 1.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Sep 2018.