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Modulation of Cognitive Flexibility by Tyrosine Depletion and Transcranial Direct Current Stimulation

NCT03462303 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 36

Last updated 2018-09-11

No results posted yet for this study

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 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

Interventions

COMBINATION_PRODUCT

Sham tDCS and tyrosine depleted drink

Transcranial direct current stimulation (sham) of the dlPFC in combination with a tyrosine and phenylalanine free product.

COMBINATION_PRODUCT

Anodal tDCS and tyrosine depleted drink

Transcranial direct current stimulation (anodal) of the dlPFC in combination with a tyrosine and phenylalanine free product.

COMBINATION_PRODUCT

Sham tDCS and balanced drink

Transcranial direct current stimulation (sham) of the dlPFC in combination with a drink containing both tyrosine and phenylalanine.

COMBINATION_PRODUCT

Anodal tDCS and balanced drink

Transcranial direct current stimulation (anodal) of the dlPFC in combination with a drink containing both tyrosine and phenylalanine.

Sponsors & Collaborators

  • Sheffield Hallam University

    lead OTHER

Study Design

Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Model
FACTORIAL

Eligibility

Min Age
18 Years
Max Age
30 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2018-02-12
Primary Completion
2018-06-30
Completion
2018-06-30

Countries

  • United Kingdom

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT03462303 on ClinicalTrials.gov