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Neuro-Cognitive Effects of Acute Tyrosine Administration on Reactive and Proactive Response Inhibition in Healthy Older Adults

46 Pages Posted: 18 Sep 2017  

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

Monja Isabel Froboese

Radboud University

Bram Bastiaan Zandbelt

Radboud University

Ondine van de Rest

Wageningen University Human Nutrition

Roshan Cools

Radboud University Medical Center

Esther Aarts

Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging

Date Written: September 14, 2017

Abstract

The aging brain is characterized by altered dopamine signaling. The amino acid tyrosine, a catecholamine precursor, is known to improve cognitive performance in young adults, especially during high environmental demands. Tyrosine administration might also affect catecholamine transmission in the aging brain, thereby improving cognitive functioning. In healthy older adults, we previously demonstrated impairments in two forms of response inhibition: reactive inhibition (outright stopping) and proactive inhibition (anticipatory response slowing) under high information load. However, no study has directly compared the effects of a catecholamine precursor on reactive and load-dependent proactive inhibition. In this study we explored the effects of tyrosine on reactive and proactive response inhibition and signal in dopaminergically innervated fronto-striatal regions. Depending on age, tyrosine might lead to beneficial or detrimental neurocognitive effects. We aimed to address these hypotheses in 24 healthy older adults (aged 61-72 years) using fMRI in a double blind, counterbalanced, placebo-controlled, within-subject design. Across the group, tyrosine did not alter reactive or proactive inhibition behaviorally, but did increase fronto-parietal proactive inhibition-related activation. When taking age into account, tyrosine affected proactive inhibition both behaviorally and neurally. Specifically, increasing age was associated with a greater detrimental effect of tyrosine compared with placebo on proactive slowing. Moreover, with increasing age, tyrosine decreased fronto-striatal and parietal proactive signal, which correlated positively with tyrosine’s effects on proactive slowing. To conclude, tyrosine negatively affected proactive response slowing and associated fronto-striatal activation in an age-dependent manner, highlighting the importance of catecholamines, perhaps particularly dopamine, for proactive response inhibition in older adults.

Suggested Citation

Bloemendaal, Mirjam and Froboese, Monja Isabel and Zandbelt, Bram Bastiaan and Ondine van de Rest and Cools, Roshan and Aarts, Esther, Neuro-Cognitive Effects of Acute Tyrosine Administration on Reactive and Proactive Response Inhibition in Healthy Older Adults (September 14, 2017). Available at SSRN: https://ssrn.com/abstract=3037114

Mirjam Bloemendaal (Contact Author)

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

Nijmegen
Netherlands

Monja Froboese

Radboud University ( email )

Nijmegen, 6500 HK
Netherlands

Bram Zandbelt

Radboud University ( email )

Nijmegen, 6500 HK
Netherlands

Ondine Rest, van de

Wageningen University Human Nutrition ( email )

Wageningen
Netherlands

Roshan Cools

Radboud University Medical Center ( email )

Esther Aarts

Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging ( email )

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