Psychopharmacology

, Volume 141, Issue 4, pp 362–369

Tryptophan depletion in normal volunteers produces selective impairment in memory consolidation

  • W. J. Riedel
  • Tineke Klaassen
  • Nicolaas E. P. Deutz
  • Astrid van Someren
  • Herman M. van Praag
ORIGINAL INVESTIGATION

DOI: 10.1007/s002130050845

Cite this article as:
Riedel, W., Klaassen, T., Deutz, N. et al. Psychopharmacology (1999) 141: 362. doi:10.1007/s002130050845
  • 185 Downloads

Abstract

Serotonin (5-hydroxytryptamine; 5-HT) circuits may play a role in cognitive performance, particularly in learning and memory. Cognitive impairment is often seen in depressed patients, in whom 5-HT turnover in the brain is thought to be lowered. A possible human pharmacological model to study the involvement of the serotonergic system in cognitive impairment is to reduce central 5-HT synthesis through L-tryptophan depletion in healthy subjects. In this study, the cognitive effects of tryptophan depletion were assessed and whether genetically or developmentally determined vulnerability factors were predictive of the cognitive impairment induced by tryptophan depletion. Sixteen healthy volunteers with a positive family history of depression and 11 without were given 100 g of an amino acid mixture with or without tryptophan, according to a double-blind, cross-over design. Tryptophan depletion specifically impaired long-term memory performance in all subjects: delayed recall performance, recognition sensitivity, and recognition reaction times were significantly impaired after tryptophan depletion relative to placebo. Short-term memory and perceptual and psychomotor functions were unchanged. There were no differences between groups with a positive and a negative family history for depression. On the basis of these results, it is concluded that tryptophan depletion specifically impairs long-term memory formation, presumably as a result of an acute decrease in 5-HT turnover in the brain.

Key words Attention Cognition disorders etiology Competing amino acids Memory disorders chemically induced Serotonin biosynthesis Serotonergic system Tryptophan metabolism Verbal learning 

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • W. J. Riedel
    • 1
  • Tineke Klaassen
    • 1
  • Nicolaas E. P. Deutz
    • 2
  • Astrid van Someren
    • 1
  • Herman M. van Praag
    • 1
  1. 1.Department of Psychiatry and Neuropsychology, Brain and Behaviour Institute, European Graduate School for Neurosciences, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The NetherlandsNL
  2. 2.Department of Surgery, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands e-mail: wim.riedel@np.unimaas.nl, Fax: +31-43-3881046NL

Personalised recommendations