title: Tyrosine promotes cognitive flexibility: evidence from proactive vs. reactive control during task switching performance.
abstract: Tyrosine (TYR), an amino acid found in various foods, has been shown to increase dopamine (DA) levels in the brain. Recent studies have provided evidence that TYR supplementation can improve facets of cognitive control in situations with high cognitive demands. Here we investigated whether TYR promotes cognitive flexibility, a cognitive-control function that is assumed to be modulated by DA. We tested the effect of TYR on proactive vs. reactive control during task switching performance, which provides a relatively well-established diagnostic of cognitive flexibility. In a double-blind, randomized, placebo-controlled design, 22 healthy adults performed in a task-switching paradigm. Compared to a neutral placebo, TYR promoted cognitive flexibility (i.e. reduced switching costs). This finding supports the idea that TYR can facilitate cognitive flexibility by repleting cognitive resources.
authors.affiliation: Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands. Electronic address: l.steenbergen@fsw.leidenuniv.nl.
authors.forename: Laura
authors.initials: L
authors.lastname: Steenbergen
authors.affiliation: Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands.
authors.forename: Roberta
authors.initials: R
authors.lastname: Sellaro
authors.affiliation: Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hommel
authors.affiliation: Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands.
authors.forename: Lorenza S
authors.initials: LS
authors.lastname: Colzato
mesh_terms: D000293:Adolescent; D001143:Arousal / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D003071:Cognition / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D056344:Executive Function / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D009483:Neuropsychological Tests; D018697:Nootropic Agents / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects; D014443:Tyrosine / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D018697:Nootropic Agents; D014443:Tyrosine
keywords: Cognitive flexibility; Dopamine; Task-switching; Tyrosine