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

Not Applicable

• Conditions: Modulation of Cognitive Flexibility by Transcranial Direct Current Stimulation, Tyrosine Administration and Polymorphisms in the COMT Gene
• Interventions: Combination Product: tdcs (sham/anodal) + drug (placebo/tyrosine)

• Registration Number: NCT03845920
• Lead Sponsor: Sheffield Hallam University

Brief Summary

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

Not available

Study Timeline

• Study First Submitted: 2019-02-11
• Study First Submitted QC: 2019-02-15
• Study Start: 2019-02-18
• Study First Posted: 2019-02-19
• Status Verified: 2019-04
• Last Update Submitted: 2019-04-02
• Last Update Posted: 2019-04-04
• Primary Completion: 2019-09-30
• Study Completion: 2019-09-30

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 32

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
tDCS anodal +tyrosine	tdcs (sham/anodal) + drug (placebo/tyrosine)	tDCS= anodal transcranial direct current stimulation of the dorsolateral prefrontal cortex drugs= tyrosine (2 grams)
tDCS sham + placebo	tdcs (sham/anodal) + drug (placebo/tyrosine)	tDCS= transcranial direct current stimulation drugs= placebo (cellulose \[2 grams\])
tDCS sham + tyrosine	tdcs (sham/anodal) + drug (placebo/tyrosine)	tDCS= transcranial direct current stimulation drugs= tyrosine (2 grams)
tDCS anodal + placebo	tdcs (sham/anodal) + drug (placebo/tyrosine)	tDCS= anodal transcranial direct current stimulation of the dorsolateral prefrontal cortex drugs= placebo (cellulose \[2 grams\])

Primary Outcome Measures

Name	Time	Method
Wisconsin Card Sorting Test (WCST) performance	Measured twice in each session (4 arms): at time 0 and 80 minutes into testing.	Measuring change in perseverative errors in the WCST
Probabilistic Reversal Learning (PRL) performance	Measured twice in each session (4 arms): at time 0 and 80 minutes into testing.	Measuring change in reversal errors in the WCST
Flanker Task performance	Measured twice in each session (4 arms): at time 0 and 80 minutes into testing.	Measuring change in conflict cost (defined as the difference in reaction time between congruent and incongruent responses)

Trial Locations

Locations (1)

Psychology labs; 🇬🇧 Sheffield, South Yorkshire, United Kingdom