Mod of Cognitive Flexibility by tDCS, Tyrosine Polymorphisms in the COMT Gene

NCT ID: NCT03845920

Last Updated: 2019-04-04

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Clinical Phase

NA

Total Enrollment

32 participants

Study Classification

INTERVENTIONAL

Study Start Date

2019-02-18

Study Completion Date

2019-09-30

Brief Summary

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The current study would examine whether increases in endogenous dopaminergic activity via tyrosine and the (presumed) excitation of these by anodal tDCS of the dlPFC could causally be related to cognitive flexibility as measured by task switching and reversal learning.

Additionally, the study will test whether the Val158Met-polymorphism in the catechol- O-methyltransferase (COMT) gene could also predict the effect of TYR supplementation, as this gene is involved in DA degradation in the prefrontal cortex.

Detailed Description

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Conditions

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Modulation of Cognitive Flexibility by Transcranial Direct Current Stimulation, Tyrosine Administration and Polymorphisms in the COMT Gene

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

DOUBLE

Participants Outcome Assessors

Study Groups

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tDCS sham + placebo

tDCS= transcranial direct current stimulation drugs= placebo (cellulose \[2 grams\])

Group Type OTHER

tdcs (sham/anodal) + drug (placebo/tyrosine)

Intervention Type COMBINATION_PRODUCT

tDCS= A DC Stimulator Plus (neuroConn, Germany) with one 5 cm x 7 cm rubber electrode (anode) and a 10 cm x 10 cm (cathode; reference electrode), encased in saline soaked sponges will be used. The anode will be positioned over the left dlPFC, centered on F3 in the 10e20 electroencephalography (EEG) system, while the cathode on the contralateral supraorbital ridge (Fp2).Current will be delivered at 1.5mA for 20 min plus 30 s fade in/fade out periods.For sham stimulation, the current will be faded in over 30 s, at 1.5mA and then will be switched off.

Drugs= 2.0 g of L-Tyrosine and 2.0 g of the placebo microcrystalline cellulose will be dissolved in 400ml of orange juice as per previously published protocols.

tDCS sham + tyrosine

tDCS= transcranial direct current stimulation drugs= tyrosine (2 grams)

Group Type EXPERIMENTAL

tdcs (sham/anodal) + drug (placebo/tyrosine)

Intervention Type COMBINATION_PRODUCT

tDCS= A DC Stimulator Plus (neuroConn, Germany) with one 5 cm x 7 cm rubber electrode (anode) and a 10 cm x 10 cm (cathode; reference electrode), encased in saline soaked sponges will be used. The anode will be positioned over the left dlPFC, centered on F3 in the 10e20 electroencephalography (EEG) system, while the cathode on the contralateral supraorbital ridge (Fp2).Current will be delivered at 1.5mA for 20 min plus 30 s fade in/fade out periods.For sham stimulation, the current will be faded in over 30 s, at 1.5mA and then will be switched off.

Drugs= 2.0 g of L-Tyrosine and 2.0 g of the placebo microcrystalline cellulose will be dissolved in 400ml of orange juice as per previously published protocols.

tDCS anodal + placebo

tDCS= anodal transcranial direct current stimulation of the dorsolateral prefrontal cortex drugs= placebo (cellulose \[2 grams\])

Group Type EXPERIMENTAL

tdcs (sham/anodal) + drug (placebo/tyrosine)

Intervention Type COMBINATION_PRODUCT

tDCS= A DC Stimulator Plus (neuroConn, Germany) with one 5 cm x 7 cm rubber electrode (anode) and a 10 cm x 10 cm (cathode; reference electrode), encased in saline soaked sponges will be used. The anode will be positioned over the left dlPFC, centered on F3 in the 10e20 electroencephalography (EEG) system, while the cathode on the contralateral supraorbital ridge (Fp2).Current will be delivered at 1.5mA for 20 min plus 30 s fade in/fade out periods.For sham stimulation, the current will be faded in over 30 s, at 1.5mA and then will be switched off.

Drugs= 2.0 g of L-Tyrosine and 2.0 g of the placebo microcrystalline cellulose will be dissolved in 400ml of orange juice as per previously published protocols.

tDCS anodal +tyrosine

tDCS= anodal transcranial direct current stimulation of the dorsolateral prefrontal cortex drugs= tyrosine (2 grams)

Group Type EXPERIMENTAL

tdcs (sham/anodal) + drug (placebo/tyrosine)

Intervention Type COMBINATION_PRODUCT

tDCS= A DC Stimulator Plus (neuroConn, Germany) with one 5 cm x 7 cm rubber electrode (anode) and a 10 cm x 10 cm (cathode; reference electrode), encased in saline soaked sponges will be used. The anode will be positioned over the left dlPFC, centered on F3 in the 10e20 electroencephalography (EEG) system, while the cathode on the contralateral supraorbital ridge (Fp2).Current will be delivered at 1.5mA for 20 min plus 30 s fade in/fade out periods.For sham stimulation, the current will be faded in over 30 s, at 1.5mA and then will be switched off.

Drugs= 2.0 g of L-Tyrosine and 2.0 g of the placebo microcrystalline cellulose will be dissolved in 400ml of orange juice as per previously published protocols.

Interventions

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tdcs (sham/anodal) + drug (placebo/tyrosine)

tDCS= A DC Stimulator Plus (neuroConn, Germany) with one 5 cm x 7 cm rubber electrode (anode) and a 10 cm x 10 cm (cathode; reference electrode), encased in saline soaked sponges will be used. The anode will be positioned over the left dlPFC, centered on F3 in the 10e20 electroencephalography (EEG) system, while the cathode on the contralateral supraorbital ridge (Fp2).Current will be delivered at 1.5mA for 20 min plus 30 s fade in/fade out periods.For sham stimulation, the current will be faded in over 30 s, at 1.5mA and then will be switched off.

Drugs= 2.0 g of L-Tyrosine and 2.0 g of the placebo microcrystalline cellulose will be dissolved in 400ml of orange juice as per previously published protocols.

Intervention Type COMBINATION_PRODUCT

Eligibility Criteria

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Inclusion Criteria

* • Either male or female

* Between 18 and 30 years
* You are in good health
* You agree to fast overnight prior to testing

Exclusion Criteria

* • Are suffering from cardiac, hepatic, renal, 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
* Drug treatment which may lower seizure threshold (i.e. epilepsy)
* Pregnancy
* Sleep deprivation (less than 6 hours a day)
* A history of migraine or headaches
* A history of taking antidepressants
* A history of taking tyrosine supplements
Minimum Eligible Age

18 Years

Maximum Eligible Age

30 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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Sheffield Hallam University

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Luca Aquili, Ph.D.

Role: PRINCIPAL_INVESTIGATOR

Sheffield Hallam University

Locations

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Psychology labs

Sheffield, South Yorkshire, United Kingdom

Site Status RECRUITING

Countries

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United Kingdom

Central Contacts

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Luca Aquili, Ph.D.

Role: CONTACT

+ 44 (0) 114 225 ext. 6991

Ann Macaskill, Ph.D.

Role: CONTACT

44 (0)114 225 ext. 4604

Facility Contacts

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Lee Wallace, BSc

Role: primary

0114 225 ext. 5953

Jordan Crawford, MSc

Role: backup

0114 225 ext. 3554

Other Identifiers

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SheffieldHallamAquili2019

Identifier Type: -

Identifier Source: org_study_id

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