Tyrosine Improves Working Memory in a Multitasking Environment

doi:10.1016/S0091-3057(99)00094-5

Pharmacology Biochemistry and Behavior

Volume 64, Issue 3, November 1999, Pages 495-500

https://doi.org/10.1016/S0091-3057(99)00094-5 Get rights and content

Abstract

Previous studies indicate that tyrosine may prove useful in promoting improved performance in situations in which performance is compromised by stress. To extend the generality of previous tyrosine findings, the present study examined the effects of tyrosine ingestion on performance during both a Multiple Task and a Simple Task battery. The multiple task battery was designed to measure working memory, arithmetic skills, and visual and auditory monitoring simultaneously, whereas the simple task battery measured only working memory and visual monitoring. Ten men and 10 women subjects underwent these batteries 1 h after ingesting 150 mg/kg of l-tyrosine or placebo. Administration of tyrosine significantly enhanced accuracy and decreased frequency of list retrieval on the working memory task during the multiple task battery compared with placebo. However, tyrosine induced no significant changes in performance on the arithmetic, visual, or auditory tasks during the Multiple Task, or modified any performance measures during the Simple Task battery. Blood levels of ACTH and cortisol were not, but heart rate and blood pressure were significantly increased during the performance tasks. The present results indicate that tyrosine may sustain working memory when competing requirements to perform other tasks simultaneously degrade performance, and that supplemental tyrosine may be appropriate for maintaining performance when mild to severe decrements are anticipated.

Section snippets

Subjects

Ten men and 10 women subjects were recruited from active duty personnel and government civilians in the Washington, DC metropolitan area. Subjects were healthy, nonsmokers, free of any regular medications or drugs, and had 20/20 or corrected 20/20 vision. The subjects averaged 28.8 ± 0.7 (mean ± SEM) years of age (range = 20–38), 176.0 ± 2.1 cm of height (range = 157.5–203.0), and 75.0 ± 2.6 kg (range = 46.5–104) of weight. The nature and risks of the study were explained and each subject

Performance on Simple and Multiple Task Batteries

Figure 1 presents total points accumulated on the Multiple and Simple Task batteries under tyrosine and placebo conditions. Overall, more points were accumulated during the Simple Task compared to the Multiple Task battery. No significant main effect of tyrosine was obtained on total points accumulated, but a trend toward greater point accumulation under tyrosine was noted for the Multiple Task battery. Inspection of the SMT data indicated an effect of tyrosine on working memory when

Discussion

The present findings suggest a unique capability of tyrosine for maintaining working memory under conditions in which physiologic indicators of stress are minimally changed and biochemical indicators are unchanged. Specifically, this study demonstrated that administration of the CA precursor, tyrosine, compared with placebo, served to prevent decrements in working memory, as indicated by performance on the Sternberg Memory Task (SMT), when subjects were required to perform multiple tasks

Acknowledgements

The opinions and assertions expressed herein are those of the authors and should not be construed as reflecting those of the Naval Medical Research Institute, the Uniformed Services University of the Health Sciences (USUHS) or the Department of Defense. This project was supported by US Special Operations Command, G19175. The authors acknowledge the excellent technical assistance provided by Lisa D. McAllister.

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Dietary and serum tyrosine, white matter microstructure and inter-individual variability in executive functions in overweight adults: Relation to sex/gender and age
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Tyrosine (tyr), the precursor of the neurotransmitter dopamine, is known to modulate cognitive functions including executive attention. Tyr supplementation is suggested to influence dopamine-modulated cognitive performance. However, results are inconclusive regarding the presence or strength and also the direction of the association between tyr and cognitive function. This pre-registered cross-sectional analysis investigates whether diet-associated serum tyr relates to executive attention performance, and whether this relationship is moderated by differences in white matter microstructure.
59 healthy, overweight, young to middle-aged adults (20 female sex/gender group, 28.3 ± 6.6 years, BMI: 27.3 ± 1.5 kg/m²) drawn from a longitudinal study reported dietary habits, donated blood and completed diffusion-weighted brain magnetic resonance imaging and the attention network test. Main analyses were performed using linear regressions and non-parametric voxel-wise inference testing.
Confirmatory analyses did neither support an association between dietary and serum tyr nor a relationship between relative serum tyr/large neutral amino acids (LNAA) levels or white matter microstructure and executive attention performance. However, exploratory analyses revealed higher tyr intake, higher serum tyr and better executive attention performance in the male sex/gender group. In addition, older age was associated with higher dietary tyr intake and lower fractional anisotropy in a widespread cluster across the brain. Finally, a positive association between relative serum tyr/LNAA level and executive attention performance was found in the male sex/gender group when accounting for age effects.
Our analysis advances the field of dopamine-modulated cognitive functions by revealing sex/gender and age differences which might be diet-related. Longitudinal or intervention studies and larger sample sizes are needed to provide more reliable evidence for links between tyr and executive attention.
Characterizing serum amino acids in schizophrenic patients: Correlations with gut microbes
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Amino acid abnormalities have been suggested to be a key pathophysiological mechanism in schizophrenia (SZ). Recently, gut microbes were found to be critically involved in mental and metabolic diseases. However, the relationship between serum amino acid levels and gut microbes in SZ is rarely studied. Here, we analyzed serum amino acid levels in 76 untreated SZ patients and 79 healthy controls (HC). Serum levels of 10 amino acids were significantly altered in patients with SZ. We further classified the cut-off values for serum arginine, leucine, glutamine, and methionine levels to distinguish SZ patients from controls. These classifiers were shown to be effective in another validation cohort (49 SZ and 48 HC). The correlation between serum amino acids and clinical symptoms and cognitive functions was also analyzed. Arginine, leucine, glutamine, and methionine levels were significantly correlated with clinical symptoms and cognitive impairments in SZ patients. By metagenome shotgun sequencing of fecal samples, we found that patients with SZ with a low level of serum amino acids have higher richness and evenness of the gut microbiota. At the genus level, the abundances of Mitsuokella and Oscillibacter are significantly abnormal. At the mOTU level, 15 mOTUs in the low-level SZ group were significantly different from the HC group. In addition, Mitsuokella multacida was correlated with glutamine and methionine, respectively. Our research revealed that alterations in serum amino acid levels are critically related to changes in gut microbiota composition in SZ patients. These findings may shed light on new strategies for the diagnosis and treatment of SZ.
Detection of L-Tyrosine by electrochemical method based on binary mixed CdO/SnO<inf>2</inf> nanoparticles
2020, Measurement: Journal of the International Measurement Confederation
Citation Excerpt :
In this approach, L-Tyr is an nonessential amino acid, chemically known as 4-hydroxyphenylalanine and used by human body cell to produce protein biologically [1,2].
Here, the nanoparticles (NPs) of CdO/SnO₂ were prepared by co-precipitation method in alkaline phase at low temperature. The characterization of CdO/SnO₂ NPs were analyzed by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analysis. To fabricate the sensor, glassy carbon electrode (GCE) was coated by CdO/SnO₂ NPs with 5% nafion suspension. The resulted sensor was applied to detect L-Tyrosine (L-Tyr) in buffer phase. A linear relation current versus concentration known as calibration curve was made. The sensor sensitivity (11.848 µA µM⁻¹ cm⁻²) is calculated from the slope of calibration curve. Recognizing the maximum linear region in calibration curve (regression coefficient R² = 0.99), the linear dynamic range (0.1 nM–0.01 mM) is used. Finally, the lower limit of detection (97.93 ± 4.89 pM) is estimated by applying the signal to noise ratio of 3 from the calibration curve. During the sensing performances, it was found as reliable, reproducible and long-term stable sensor and validated to detect the real biological samples by electrochemical approach in room conditions.
Tyrosine negatively affects flexible-like behaviour under cognitively demanding conditions
2020, Journal of Affective Disorders
Citation Excerpt :
Non-aversive stimuli such as high cognitive demand have also been hypothesized to lead to similar catecholaminergic depletion (Jongkees et al., 2015), but this has been hardly investigated. Thomas et al. (1999) were the first to show that tyrosine improved working memory performance only when performing multiple tasks simultaneously. Finding out whether tyrosine has enhancing effects only under particularly challenging conditions such as high cognitive load would be important as it would confirm that catecholaminergic depletion can be reversed both when individuals are exposed to overt and non-overt stressors.
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.
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.
Contrary to expectations, we found that instead of ameliorating performance under the high cognitive load condition, tyrosine worsened cognitive flexibility.
Physiological marker of stress was not measured.
Our results suggest that aversive stressors and cognitive demand modulate the effects of tyrosine on cognitive performance in a differential manner.
Influence of nutritional tyrosine on cognition and functional connectivity in healthy old humans
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Tyrosine is precursor for monoamine neurotransmitters such as dopamine (DA), which is one of the key neurotransmitters in the frontostriatal network and of crucial relevance for mental disorders. Recent research reported that high dose tyrosine application resulted in increased brain DA synthesis, which is consistent with the observation of positive associations between daily tyrosine intake and cognitive test performance. In the present study, we investigated the associations between working memory (WM) dependent tasks and self-reported nutritional tyrosine intake within a large group of healthy elderly humans (286 subjects) by additionally including brain functional data. We observed a negative correlation between tyrosine intake and resting-state functional connectivity (rsFC) between the striatum (putamen) and the prefrontal cortex. That is to say, we found higher rsFC in individuals consuming less tyrosine per day. At the same time, this increasedrsFC or hyperconnectivity was associated with lower WM performance. These findings suggest that lower or insufficient supply of tyrosine might result in dysfunctional connectivity between striatal and frontal regions leading to lower WM capacity in healthy elderly humans.
Poor cognitive ageing: Vulnerabilities, mechanisms and the impact of nutritional interventions
2018, Ageing Research Reviews
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This review aims to summarise the current state of knowledge of vulnerabilities that predispose towards dysfunctional brain ageing, highlight potential protective mechanisms, and discuss dietary interventions that may be used as therapies. A special focus of this paper is on the impact of nutrition on neuroprotection and the underlying molecular mechanisms, and this focus reflects the discussions held during the 2nd workshop ‘Nutrition for the Ageing Brain: Functional Aspects and Mechanisms’ in Copenhagen in June 2016. The present review is the most recent in a series produced by the Nutrition and Mental Performance Task Force under the auspice of the International Life Sciences Institute Europe (ILSI Europe).
Coupling studies of cognitive ageing with studies investigating the effect of nutrition and dietary interventions as strategies targeting specific mechanisms, such as neurogenesis, protein clearance, inflammation, and non-coding and microRNAs is of high value. Future research on the impact of nutrition on cognitive ageing will need to adopt a longitudinal approach and multimodal nutritional interventions will likely need to be imposed in early-life to observe significant impact in older age.

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¹: Formerly with the Thermal Stress Division, Naval Medical Research Institute, Bethesda, MD 20889-5607.

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ArticlesTyrosine Improves Working Memory in a Multitasking Environment

Abstract

Section snippets

Subjects

Performance on Simple and Multiple Task Batteries

Discussion

Acknowledgements

Brain Res.

Brain Res. Bull.

Physiol. Behav.

Neuropharmacology

Biochem. Pharmacol.

Life Sci.

Physiol Behav.

Pharmacol. Biochem. Behav.

Effect of tyrosine on cognitive function and blood pressure under stress

Brain Res. Bull.

SYNWORK1A pc-based tool for assessment of performance in a simulated work environment

Behav. Res. Methods Instrum. Comput.

Stress and monoamine neurons in the brain

The effects of tyrosine on cognitive performance during extended wakefulness

Aviat. Space Environ. Med.

Articles
Tyrosine Improves Working Memory in a Multitasking Environment