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Cited by 16Thyroid Disorders and TreatmentsSpaceflight effects on biologyStress Responses and Cortisol

Psychoneuroendocrine effects of combined thyroxine and triiodothyronine versus tyrosine during prolonged Antarctic residence

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Palinkas, Lawrence A., Reedy, Kathleen R., Smith, Mark, Anghel, Mihai, Steel, Gary D., Reeves, Dennis, Shurtleff, David, Case, H. Samuel +2 more·2007·International Journal of Circumpolar Health
DOI 10.3402/ijch.v66i5.18312
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Abstract

OBJECTIVES: We previously reported that cognitive function improves with thyroxine and that there is a circannual pattern to mood and human TSH during Antarctic residence. To extend these findings, we examined the effects of tyrosine and a combined levothyroxine/liothyronine supplement in euthyroid men and women who spent the austral summer (n = 43) and/or winter (n = 42) in Antarctica. STUDY DESIGN: Randomized, placebo-controlled, clinical trial. METHODS: Subjects were randomized to receive the following each day for 91.6 +/- 3.2 days in summer and/or 138.0 +/- 3.2 days in winter: (1) 12g tyrosine mixed in 113g applesauce; (2) 50 microg of levothyroxine and 12.5 microg of liothyronine (T4-T3 Supplement); or (3) placebo. Cognitive performance and mood were assessed using the Automatic Neuropsychological Assessment Metric - Isolated and Confined Environments. RESULTS: With placebo in summer, mood did not change while TSH decreased by 28%; in winter, there was a 136% degradation in mood (p < 0.01) and TSH increased by 18%. With combined T4-T3 supplement, there was a 51% degradation in mood in summer compared with placebo (p < 0.05) and TSH decreased by 57%; in winter there was a 135% degradation in mood while TSH was reduced by 26% (p < 0.05). Tyrosine use in summer was associated with no change in mood and a 30% decline in TSH, while in winter there was a 47% improvement in mood and TSH decreased by 28% along with a 6% increase in fT3 (p < 0.05). CONCLUSIONS: Administration of tyrosine leads to a significant reduction in serum TSH and improvement in mood in winter compared with placebo, while the combined T4-T3 supplement leads to a worsening of mood in summer and no improvement in winter. There appears to be a seasonal influence on the psychological response to interventions and the relationship to changes in TSH reductions.

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  • All reviewed studies except one used a within-subjects design with a counterbalanced treatment order.

    “All studies except one (Palinkas et al., 2007) used a within-subjects design with a counterbalanced treatment order.”

    From Behavioral and cognitive effects of tyrosine intake in healthy human adults (2015) · cites this paper as Palinkas et al., 2007

  • In the Antarctica study, plasma norepinephrine levels declined more in the tyrosine group than in the placebo group during winter.

    “In the Antarctica study, plasma norepinephrine levels declined more in the tyrosine group than in the placebo group during the winter.”

    From Behavioral and cognitive effects of tyrosine intake in healthy human adults (2015) · cites this paper as Palinkas et al., 2007

  • Only one reviewed study involved repeated tyrosine dosing over multiple days or daily supplementation over multiple weeks.

    “Our literature search yielded only one study which involved repeated tyrosine dosing over multiple days (Palinkas et al., 2007).”

    From Behavioral and cognitive effects of tyrosine intake in healthy human adults (2015) · cites this paper as Palinkas et al., 2007

  • In the only longitudinal study, tyrosine or placebo was supplemented for two seasons to research station residents in Antarctica.

    “In the only study to use a longitudinal design, tyrosine or placebo was supplemented for two seasons to research station residents in Antarctica (Palinkas et al., 2007).”

    From Behavioral and cognitive effects of tyrosine intake in healthy human adults (2015) · cites this paper as Palinkas et al., 2007

  • The Antarctica study reported lower serum thyroid-stimulating hormone and higher plasma free triiodothyronine levels as a result of tyrosine supplementation during winter, with no effects during summer.

    “The Antarctica study reported lower serum thyroid-stimulating hormone and higher plasma free triiodothyronine levels as a result of tyrosine supplementation during the winter season, with no effects during the summer (Palinkas et al., 2007).”

    From Behavioral and cognitive effects of tyrosine intake in healthy human adults (2015) · cites this paper as Palinkas et al., 2007

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Authors
Palinkas, L. A., Reedy, K. R., Smith, M., Anghel, M., Steel, G. D., Reeves, D., Shurtleff, D., Case, H. S., Do, N. V., & Reed, H. L.
Affiliations
  • University of Southern California (US)
  • United States Food and Drug Administration (US)
  • George Washington University (US)
  • University of California San Diego (US)
  • Lincoln University (NZ)
  • Clinvest (United States) (US)
  • McDaniel College (US)
  • Madigan Army Medical Center (US)
  • MultiCare Health System (US)
Corresponding author
Palinkas, Lawrence A.
ORCID
Venue
International Journal of Circumpolar Health
Publisher
Informa UK Limited
Published
2007-12
Volume
66
Issue
5
Pages
402-417
ISSN
  • 1239-9736 (ISSN-L)
  • 2242-3982
DOI
10.3402/ijch.v66i5.18312
OpenAlex
W2072584860
Cited by
16
References
47
Citations by year
2024: 2 · 2022: 1 · 2021: 1 · 2018: 2 · 2017: 3 · 2016: 1 · 2015: 3
FWCI
0.49
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • International Journal of Circumpolar Health (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
National Science Foundation
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Health Sciences › Medicine › Physiology › Spaceflight effects on biology
  • Life Sciences › Neuroscience › Behavioral Neuroscience › Stress Responses and Cortisol
Keywords
thyroxine, triiodothyronine, tyrosine supplementation, levothyroxine, liothyronine, thyroid-stimulating hormone, mood, cognitive performance, Antarctic expedition, seasonal variation, isolated and confined environments
MeSH terms
Adult, Affect, Antarctic Regions, Cognition, Drug Combinations, Female, Humans, Male, Seasons, Thyroid Hormones, Thyrotropin, Thyroxine, Triiodothyronine, Tyrosine

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