Tyrosine negatively affects flexible-like behaviour under cognitively demanding conditions

ROBSON, Anna, LIM, Lee Wei and AQUILI, Luca (2019). Tyrosine negatively affects flexible-like behaviour under cognitively demanding conditions. Journal of Affective Disorders, 260, 329-333.

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Official URL: https://www.sciencedirect.com/science/article/pii/...
Link to published version:: https://doi.org/10.1016/j.jad.2019.09.031

Abstract

Background The catecholaminergic precursor to dopamine, tyrosine, is an important modulator of cognitive performance. A number of studies have demonstrated that the beneficial effects of tyrosine on cognitive performance are most pronounced when individuals are exposed to stressful situations, such as hypothermia. However, little is known about whether manipulation of stress using non-aversive stimuli, such as cognitive demand, can also bring about similar improvements. Methods We conducted a randomized, double-blind, placebo-controlled experiment to test the effects of tyrosine administration and cognitive load (low or high) on cognitive flexibility, a measure known to be influenced by catecholaminergic function. A total of 70 healthy volunteers completed a baseline cognitive flexibility test (Wisconsin Card Sorting Test: WCST). Participants were given a dose of either tyrosine (2.0 g) or placebo (cellulose) and subject to either low cognitive load (simple reaction time task) or high cognitive load (digit memory span task), immediately followed by a WCST for a second time. Results Contrary to expectations, we found that instead of ameliorating performance under the high cognitive load condition, tyrosine worsened cognitive flexibility. Limitations Physiological marker of stress was not measured. Conclusions Our results suggest that aversive stressors and cognitive demand modulate the effects of tyrosine on cognitive performance in a differential manner.

Item Type: Article
Additional Information: ** Article version: AM ** Embargo end date: 12-09-2020 ** From Elsevier via Jisc Publications Router ** Licence for AM version of this article starting on 12-09-2020: http://creativecommons.org/licenses/by-nc-nd/4.0/ **Journal IDs: issn 01650327 **History: issue date 01-01-2020; published_online 12-09-2019; accepted 03-09-2019
Identification Number: https://doi.org/10.1016/j.jad.2019.09.031
Page Range: 329-333
SWORD Depositor: Helen Garner
Depositing User: Helen Garner
Date Deposited: 07 Oct 2019 10:33
Last Modified: 07 Oct 2019 10:33
URI: http://shura.shu.ac.uk/id/eprint/25138

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