title: The acute transient polymorphic psychosis: a biochemical subtype of the cycloid psychosis.
abstract: BACKGROUND
  The pathogenesis of atypical psychoses, in particularly those characterized by polymorphic psychopathology, is hypothesized to be related to disturbances in amino acid metabolism.
  
  
  OBJECTIVE
  In the present study, the role of the amino acid serine was investigated in patients with acute transient polymorphic psychosis.
  
  
  METHODS
  Patients were loaded with serine and with the amino acids glycine and alanine as controls and subsequently evaluated for the development of psychopathological symptoms. In addition, plasma levels of amino acids were measured.
  
  
  RESULTS
  In a subgroup of patients suffering from atypical psychoses, this biochemical challenge resulted in the reappearance of psychedelic symptoms in particular. Furthermore, significantly lower plasma concentrations of serine were found. In vitro experiments revealed a disturbance in the one-carbon metabolism. In another group of patients the loading provoked vegetative symptoms and fatigue.
  
  
  CONCLUSIONS
  Disturbances in amino acid metabolism may be involved in the emergence of certain psychotic disorders.
authors.affiliation: 1Faculty of Medicine and Health Sciences, Erasmus University Medical Center, Rotterdam.
authors.forename: L
authors.initials: L
authors.lastname: Pepplinkhuizen
authors.affiliation: 2Vincent van Gogh Institute for Psychiatry, Venray, the Netherlands.
authors.forename: F M M A
authors.initials: FM
authors.lastname: van der Heijden
authors.affiliation: 2Vincent van Gogh Institute for Psychiatry, Venray, the Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Tuinier
authors.affiliation: 1Faculty of Medicine and Health Sciences, Erasmus University Medical Center, Rotterdam.
authors.forename: W M A
authors.initials: WM
authors.lastname: Verhoeven
authors.affiliation: 1Faculty of Medicine and Health Sciences, Erasmus University Medical Center, Rotterdam.
authors.forename: D
authors.initials: D
authors.lastname: Fekkes