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. Nutrients2017, 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.
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. Nutrients2017, 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.
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
Subject
Medicine and Pharmacology, Dietetics and Nutrition
Copyright:
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