TY - JOUR
T1 - Tyrosine negatively affects flexible-like behaviour under cognitively demanding conditions
AU - Robson, Anna
AU - Lim, Lee Wei
AU - Aquili, Luca
N1 - Publisher Copyright:
© 2019
PY - 2020/1/1
Y1 - 2020/1/1
N2 - 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.
AB - 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.
KW - Cognitive flexibility
KW - Dopamine
KW - Tyrosine
UR - http://www.scopus.com/inward/record.url?scp=85072048083&partnerID=8YFLogxK
U2 - 10.1016/j.jad.2019.09.031
DO - 10.1016/j.jad.2019.09.031
M3 - Article
C2 - 31521870
AN - SCOPUS:85072048083
SN - 0165-0327
VL - 260
SP - 329
EP - 333
JO - Journal of Affective Disorders
JF - Journal of Affective Disorders
ER -