title: Behavioural effects of acute phenylalanine and tyrosine depletion in healthy male volunteers.
abstract: 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 PT- mixture 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 PT- mixture 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.
authors.affiliation: Departamento de Psiquiatria, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul e Hospital de Clinicas de Porto Alegre, Brazil. grevet@terra.com.br
authors.forename: Eugenio H
authors.initials: EH
authors.lastname: Grevet
authors.forename: Marcos R
authors.initials: MR
authors.lastname: Tietzmann
authors.forename: Flávio M
authors.initials: FM
authors.lastname: Shansis
authors.forename: Caroline
authors.initials: C
authors.lastname: Hastenpflugl
authors.forename: Luiz C
authors.initials: LC
authors.lastname: Santana
authors.forename: Leticia
authors.initials: L
authors.lastname: Forster
authors.forename: Flávio
authors.initials: F
authors.lastname: Kapczinskil
authors.forename: Ivan
authors.initials: I
authors.lastname: Izquierdo
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D001288:Attention / Q000502:physiology; D001519:Behavior / Q000502:physiology*; D018592:Cross-Over Studies; D004032:Diet; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D010649:Phenylalanine / Q000097:blood / Q000172:deficiency / Q000502:physiology*; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000502:physiology; D014443:Tyrosine / Q000097:blood / Q000172:deficiency / Q000502:physiology*
chemical_list: D014443:Tyrosine; D010649:Phenylalanine