Behavioural effects of acute phenylalanine and tyrosine depletion in healthy male volunteers Journal Articles uri icon

  • Overview
  • Research
  • Identity
  • Additional Document Info
  • View All


  • Acute phenylalanine and tyrosine depletion (APTD) studies have been used to assess the role of the cathecholaminergic system in various aspects of human behaviour. In this study we conducted a randomized, double-blind, controlled and cross-over comparison to evaluate the effects of APTD on memory, attention and mood in normal subjects. Twelve healthy male volunteers were included in this study. The subjects ingested a nutritionally balanced mixture (B) or a similar mixture deficient in phenylalanine and tyrosine (PT). Before and 5 h after ingestion of the drink, volunteers underwent tests on mood, memory and attention. Results of the memory tests showed that PTmixture impaired word recall as measured in Rey's test (p = 0.016). The assessment of changes in mood showed that the balanced mixture improved scores of as alertness (VAMS factor I, p = 0.037) and the PTmixture induces an opposite effect, increased scores of anxiety (Profiles of Mental State composed-anxious dimension, p= 0.022). These results suggest that tyrosine plasma levels and cathecholamines may be important factors in regulating mood and memory.


  • Grevet, Eugenio H
  • Tietzmann, Marcos R
  • Shansis, Flávio M
  • Hastenpflug, Caroline
  • Santana, Luiz C
  • Forster, Letícia
  • Kapczinski, Flavio
  • Izquierdo, Ivan

publication date

  • January 2002