Dose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in Aging

33 Pages Posted: 21 May 2017 Last revised: 18 Sep 2017

See all articles by Ondine van de Rest

Ondine van de Rest

Wageningen University Human Nutrition

Mirjam Bloemendaal

Radboud University, Faculty of Science, Mathematics and Computing Science, Donders Institute for Brain, Cognition and Behaviour; Radboud University Medical Center, Department of Geriatric Medicine, Radboud Alzheimer Center

Rianne de Heus

Radboud University Nijmegen - Radboud University Medical Center; Wageningen University and Research (WUR)

Esther Aarts

Radboud University Nijmegen - Donders Institute for Brain, Cognition and Behaviour

Date Written: May 19, 2017

Abstract

The effects of tyrosine on plasma response and cognition in aging are unknown. We assessed the dose-dependent response to tyrosine administration in older adults in both plasma tyrosine concentrations and working memory performance. In this double blind randomized cross-over trial 17 older adults (aged 60-75 years) received a single administration of 100, 150 or 200 mg/kg body weight of tyrosine. For comparison, 17 young adults (aged 18-35 years) received a dose of 150 mg/kg body weight of tyrosine. Tyrosine plasma concentrations were determined before and 90, 120, 150, 180, 210 and 240 minutes after tyrosine intake. Working memory was assessed using the N-back task at 90 minutes after tyrosine administration. Older adults showed a dose-dependent increase in plasma tyrosine concentrations (p<.001), and the plasma response was higher than for young adults with the same dose (p<.001). Load-dependent working memory performance decreased with higher doses of tyrosine (p=.048), especially in older adults with greater dose-dependent plasma tyrosine responses (p=.035). Our results show an age-related increase in plasma tyrosine response, which was associated with a dose-dependent decline in cognitive functioning in older adults.

Keywords: tyrosine, dose-response, aging, working memory, plasma amino acids, catecholamines, dopamine

Suggested Citation

Rest, van de, Ondine and Bloemendaal, Mirjam and de Heus, Rianne and Aarts, Esther, Dose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in Aging (May 19, 2017). Available at SSRN: https://ssrn.com/abstract=2970888 or http://dx.doi.org/10.2139/ssrn.2970888

Ondine Rest, van de (Contact Author)

Wageningen University Human Nutrition ( email )

Wageningen
Netherlands

Mirjam Bloemendaal

Radboud University, Faculty of Science, Mathematics and Computing Science, Donders Institute for Brain, Cognition and Behaviour ( email )

Montessorilaan 3
Nijmegen, 6525 HR
Netherlands

Radboud University Medical Center, Department of Geriatric Medicine, Radboud Alzheimer Center

Geert Grooteplein Zuid 10
Nijmegen
Netherlands

Rianne De Heus

Radboud University Nijmegen - Radboud University Medical Center ( email )

Geert Grooteplein Zuid 10
6525 GA Nijmegen
Netherlands

Wageningen University and Research (WUR) ( email )

Hollandseweg 1
Wageningen, 6706KN
Netherlands

Esther Aarts

Radboud University Nijmegen - Donders Institute for Brain, Cognition and Behaviour ( email )

Montessorilaan 3
Radboud, 6525 HR
Netherlands

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