Preprint Article Version 1 This version not peer reviewed

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

Version 1 : Received: 18 September 2017 / Approved: 18 September 2017 / Online: 18 September 2017 (15:48:07 CEST)

A peer-reviewed article of this Preprint also exists.

van de Rest, O.; Bloemendaal, M.; de Heus, R.; Aarts, E. Dose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in Aging. Nutrients 2017, 9, 1279. van de Rest, O.; Bloemendaal, M.; de Heus, R.; Aarts, E. Dose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in Aging. Nutrients 2017, 9, 1279.

Journal reference: Nutrients 2017, 9, 1279
DOI: 10.3390/nu9121279

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.

Subject Areas

tyrosine; dose-response; aging; working memory; plasma amino acids; catecholamines; dopamine

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