Psychopharmacology

, Volume 142, Issue 1, pp 24–30 | Cite as

The effects of tryptophan depletion and loading on laboratory aggression in men: time course and a food-restricted control

  • J. M. Bjork
  • Donald M. Dougherty
  • F. Gerard Moeller
  • Don R. Cherek
  • Alan C. Swann
ORIGINAL INVESTIGATION

Abstract

Some studies have shown that sharp reduction of L-tryptophan (Trp) concentration in plasma results in increases in laboratory-measured aggression. Conversely, raising plasma Trp has blunted aggression. These effects are presumably due to impaired or enhanced serotonin synthesis and neurotransmission in the brain. In this study, the laboratory-measured aggressive behavior of eight men under both Trp depletion (T-) and Trp loading (T+) conditions was compared to their aggressive behavior under food-restricted control conditions (overnight fast without an amino acid beverage). Subjects were provoked by periodic subtraction of money which was attributed to a fictitious other participant, and aggression was defined as the number of retaliatory responses the subject made ostensibly to reduce the earnings of the (fictitious) other participant. Following ingestion of the T- beverage, aggressive responding was significantly elevated relative to the food-restricted control condition, and this increased aggressive behavior became more pronounced across behavioral testing sessions on a time-course which paralleled previously documented decreases in plasma Trp concentrations. In contrast, no changes were observed in aggressive responding under T+ conditions relative to food-restricted conditions. These within-subject behavioral changes under depleted plasma Trp conditions support earlier indications of a role of serotonin in regulating aggression.

Key words Aggression Tryptophan Serotonin Human Diet 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • J. M. Bjork
    • 1
  • Donald M. Dougherty
    • 1
  • F. Gerard Moeller
    • 1
  • Don R. Cherek
    • 1
  • Alan C. Swann
    • 1
  1. 1.Department of Psychiatry and Behavioral Sciences, University of Texas, Houston Medical School, 1300 Moursund, Houston, TX 77030, USAUS

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