title: Disturbed Serotonergic Neurotransmission and Oxidative Stress in Elderly Patients with Delirium.
abstract: BACKGROUND
  Oxidative stress and disturbances in serotonergic and dopaminergic neurotransmission may play a role in the pathophysiology of delirium.
  
  
  OBJECTIVE
  In this study, we investigated levels of amino acids, amino acid ratios and levels of homovanillic acid (HVA) as indicators for oxidative stress and disturbances in neurotransmission.
  
  
  METHODS
  Plasma levels of amino acids, amino acid ratios and HVA were determined in acutely ill patients aged ≥65 years admitted to the wards of Internal Medicine and Geriatrics of the Erasmus University Medical Center and the ward of Geriatrics of the Havenziekenhuis, Rotterdam, The Netherlands. Differences in the biochemical parameters between patients with and without delirium were investigated by analysis of variance in models adjusted for age, gender and comorbidities.
  
  
  RESULTS
  Of the 86 patients included, 23 had delirium. In adjusted models, higher mean phenylalanine/tyrosine ratios (1.34 vs. 1.14, p = 0.028), lower mean tryptophan/large neutral amino acids ratios (4.90 vs. 6.12, p = 0.021) and lower mean arginine levels (34.8 vs. 45.2 µmol/l, p = 0.022) were found in patients with delirium when compared to those without. No differences were found in HVA levels between patients with and without delirium.
  
  
  CONCLUSIONS
  The findings of this study suggest disturbed serotonergic neurotransmission and an increased status of oxidative stress in patients with delirium.
authors.affiliation: Section of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Angelique
authors.initials: A
authors.lastname: Egberts
authors.affiliation: Department of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Durk
authors.initials: D
authors.lastname: Fekkes
authors.affiliation: Section of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Eline H A
authors.initials: EH
authors.lastname: Wijnbeld
authors.affiliation: Section of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Milly A
authors.initials: MA
authors.lastname: van der Ploeg
authors.affiliation: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Jan L C M
authors.initials: JL
authors.lastname: van Saase
authors.affiliation: Section of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Gijsbertus
authors.initials: G
authors.lastname: Ziere
authors.affiliation: Section of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Tischa J M
authors.initials: TJ
authors.lastname: van der Cammen
authors.affiliation: Section of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Francesco U S
authors.initials: FU
authors.lastname: Mattace-Raso
keywords: Amino acids; Arginine; Delirium; Homovanillic acid; Oxidative stress; Serotonin; Tetrahydrobiopterin; Tryptophan