Mood Disorders / Depression Treatment / Schizophrenia
Research Summary

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References
  • Fernstrom JD. Aromatic amino acids and monoamine synthesis in the central nervous system: influence of the diet. J Nutr Biochem 1990;1:508–17.

Though the competitive transport of tryptophan and tyrosine into the CNS is subject to diet-induced changes in the LNAA pattern, it is also subject to any other metabolic phenomenon that influences the serum LNAA pattern. Consequently, transmitter synthesis rate can be directly influenced by variations in the local precursor pool size.

  • Christian Hensel et al. Influence of nutritional tyrosine on cognition and functional connectivity in healthy old humans. Neuroimage. 2019 Jun;193:139-145.
  • Ille R. “Add-On”-therapy with an individualized preparation consisting of free amino acids for patients with a major depression.  Eur Arch Psychiatry Clin Neurosci. 2007 Jun;257(4):222-9.
  • Agudelo LZ.  Skeletal muscle PGC-1α1 modulates kynurenine metabolism and mediates  resilience  to stress-induceddepression  Cell. 2014 Sep 25;159(1):33-45 
  • Katy A van Galen et al. The role of central dopamine and serotonin in human obesity: lessons learned from molecular neuroimaging studies. Metabolism. 2018 Aug;85:325-339.
  • Buist R. The therapeutic predictability of tryptophan and tyrosine in the treatment of depression. Int J Clin Nutr Rev. 1983, 3:1-3
  • Young SN. The role of serotonin in human mood and social interaction. Insight from altered tryptophan levels. Pharmacol Biochem Behav. 2002 Apr;71(4):857-65.

Reuptake inhibitors do not increase the total number of monoamine molecules in the central nervous system. Their mechanism of action facilitates redistribution of monoamines from one place to another.

  • Ghadirian AM.  Efficacy of light versus tryptophan therapy in seasonal affective disorder. J Affect Disord. 1998;50:23-27
  • Steinberg S et al.  A placebo-controlled study of the effects of L-tryptophan in patients with premenstrual dysphoria. Adv Exp Med Biol 1999; 467:85-88
  • Heresco-Levy U. Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia. Br J Psychiatry. 1996 Nov;169(5):610-7.

Glycine was well tolerated, resulted in significantly increased serum glycine levels and induced a mean 36 (7%) reduction in negative symptoms (P < 0.0001). Significant improvements were also induced in depressive and cognitive symptoms. The greatest reduction in negative symptoms was registered in the patients who had the lowest baseline serum glycine levels.

  • Heresco-Levy U. Efficacy of high-dose glycine in the treatment of enduring negative symptoms of schizophrenia. Arch Gen Psychiatry. 1999 Jan;56(1):29-36.
  • Gelenberg A. Tyrosine for depression. J Psychiatr Res. 1982- 1983;17:175-180.
  • Banderet LE. Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans. Brain Res Bull. 1989;22:759-762.
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