Contribution of L-Tyrosine to Human Decision Making in Stressful Situations (TYRO-STRESS)

L-tyrosine is a chemical precursor of dopamine. Under specific conditions, tyrosine administration can increase brain dopamine levels and therefore several studies have explored whether tyrosine supplementation can have a beneficial effect on cognitive and behavioural performance that is dependent on dopaminergic function. However, the effects of tyrosine supplementation are mixed: some studies show positive effects while others do not. Stress leads to an increase in dopaminergic activity and turnover in the brain, resulting in a decrease in brain dopamine levels. We propose to study the contribution of tyrosine to decision making and more particularly to the processes of response selection (mediated by the prefrontal cortex and under the influence of the dopaminergic system) in stressful situations.

Study Overview

• Status: Completed
• Conditions: Stress, Psychological
• Intervention / Treatment: Biological: Blood collection; Drug: L-Tyrosine 500 Mg; Behavioral: Cognitive tasks; Behavioral: Anxiety scale; Device: Electromyography (EMG); Device: Electroencephalography (EEG); Other: Stress exposure; Drug: Placebo

• Study Type: Interventional
• Enrollment (Actual): 17
• Phase: Not Applicable

Contacts and Locations

Study Locations

• France
  • Brétigny-sur-Orge, France, 91223
    • Institut de Recherche Biomédicale des Armées

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years to 61 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• From 18 to 65 years of age

Exclusion Criteria:

• Tyrosine intake within the previous 15 days
• History of neurological or psychiatric disorder
• History of nephrological or endocrine disorder or liver failure
• Hereditary tyrosinemia

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Tyrosine - Test; 4 similar visits (day 0, day 3, day 6, day 9): Administration of L-tyrosine No stress exposure	Biological: Blood collection; A blood sample will be collected before and after treatment administration; Drug: L-Tyrosine 500 Mg; The participants will be administered 4 capsules of L-Tyrosine 500 mg per oral route; Behavioral: Cognitive tasks; The participants will perform cognitive decision-making tasks: Simon task and masking task after treatment administration; Behavioral: Anxiety scale; Spielberger's State Trait Anxiety Inventory (STAI) will be filled by the participants before and after cognitive tasks; Device: Electromyography (EMG); Electromyography measurements will be performed during cognitive tasks.; Device: Electroencephalography (EEG); Electroencephalography measurements will be performed during cognitive tasks.
Experimental: Tyrosine - Stress; 4 similar visits (day 0, day 3, day 6, day 9): Administration of L-tyrosine Stress exposure	Biological: Blood collection; A blood sample will be collected before and after treatment administration; Drug: L-Tyrosine 500 Mg; The participants will be administered 4 capsules of L-Tyrosine 500 mg per oral route; Behavioral: Cognitive tasks; The participants will perform cognitive decision-making tasks: Simon task and masking task after treatment administration; Behavioral: Anxiety scale; Spielberger's State Trait Anxiety Inventory (STAI) will be filled by the participants before and after cognitive tasks; Device: Electromyography (EMG); Electromyography measurements will be performed during cognitive tasks.; Device: Electroencephalography (EEG); Electroencephalography measurements will be performed during cognitive tasks.; Other: Stress exposure; Unpleasant but not painful skin stimulations will be administered to the participants at variable intervals on the left leg during the cognitive tasks
Experimental: Placebo - Test; 4 similar visits (day 0, day 3, day 6, day 9): Administration of Placebo No stress exposure	Biological: Blood collection; A blood sample will be collected before and after treatment administration; Behavioral: Cognitive tasks; The participants will perform cognitive decision-making tasks: Simon task and masking task after treatment administration; Behavioral: Anxiety scale; Spielberger's State Trait Anxiety Inventory (STAI) will be filled by the participants before and after cognitive tasks; Device: Electromyography (EMG); Electromyography measurements will be performed during cognitive tasks.; Device: Electroencephalography (EEG); Electroencephalography measurements will be performed during cognitive tasks.; Drug: Placebo; The participants will be administered 4 capsules of Lactose 500 mg (placebo) per oral route
Experimental: Placebo - Stress; 4 similar visits (day 0, day 3, day 6, day 9): Administration of Placebo Stress exposure	Biological: Blood collection; A blood sample will be collected before and after treatment administration; Behavioral: Cognitive tasks; The participants will perform cognitive decision-making tasks: Simon task and masking task after treatment administration; Behavioral: Anxiety scale; Spielberger's State Trait Anxiety Inventory (STAI) will be filled by the participants before and after cognitive tasks; Device: Electromyography (EMG); Electromyography measurements will be performed during cognitive tasks.; Device: Electroencephalography (EEG); Electroencephalography measurements will be performed during cognitive tasks.; Other: Stress exposure; Unpleasant but not painful skin stimulations will be administered to the participants at variable intervals on the left leg during the cognitive tasks; Drug: Placebo; The participants will be administered 4 capsules of Lactose 500 mg (placebo) per oral route

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Reaction Time	Reaction Time at the cognitive tasks	At day 9 (9 days after enrollment)
Number of incorrect responses	Number of incorrect responses at the cognitive tasks	At day 9

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Error negativity	Error negativity on motor evoked potentials (measured by EMG)	At day 9
Correlation coefficient between anxiety level and tyrosinemia	Correlation coefficient between anxiety level (measured by anxiety scale) and tyrosinemia (measured in blood sample)	At day 9
Correlation coefficient between anxiety level and plasma tyrosine	Correlation coefficient between anxiety level (measured by anxiety scale) and plasma tyrosine (measured in blood sample)	At day 9
Correlation coefficient between cortisolaemia and melatoninaemia	Correlation coefficient between cortisolaemia and melatoninaemia (measured in blood sample)	At day 9

Collaborators and Investigators

• Sponsor: Direction Centrale du Service de Santé des Armées

Study record dates

Study Major Dates

• Study Start (Actual): November 18, 2021
• Primary Completion (Actual): April 7, 2022
• Study Completion (Actual): April 7, 2022

Study Registration Dates

• First Submitted: August 15, 2020
• First Submitted That Met QC Criteria: August 15, 2020
• First Posted (Actual): August 19, 2020

Study Record Updates

• Last Update Posted (Actual): November 25, 2022
• Last Update Submitted That Met QC Criteria: November 23, 2022
• Last Verified: November 1, 2022

More Information

Terms related to this study

• Keywords: L-tyrosine
• Additional Relevant MeSH Terms: Behavioral Symptoms; Stress, Psychological
• Other Study ID Numbers: 2018PPRC25; 2019-A03194-53 (Other Identifier: IDRCB)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Undecided

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No