Tryptophan depletion and aggressive responding in healthy males

F. Gerard Moeller, Donald M. Dougherty, Alan C. Swann, Diana Collins, Chester M. Davis, Don R. Cherek

Research output: Contribution to journalArticlepeer-review

88 Scopus citations


In order to study the effect of decreasing plasma tryptophan levels on aggressive responding in a controlled laboratory setting, we administered two doses (25 g and 100 g) of a tryptophan-free amino acid mixture to ten healthy male subjects after 24 h of a low tryptophan diet. Subjects were screened for current or past psychiatric, or non-psychiatric medical illness. Aggressive responding on. free-operant laboratory measure of aggression (the Point Subtraction Aggression Paradigm) and plasma tryptophan levels were measured before and after drinking the amino acid mixture. There was a significant increase in aggressive responding 5 h after the 100 g mixture and a significant increase in aggressive responding 6 h after the 25 g mixture compared to a baseline day when no drink was administered. There was also a significant decrease in plasma tryptophan at 5 hours after ingestion compared to baseline for both doses of amino acid mixture. This study supports the hypothesis that tryptophan depletion increases aggressive responding in healthy males in a laboratory setting, probably by decreasing brain serotonin.

Original languageEnglish (US)
Pages (from-to)97-103
Number of pages7
Issue number2
StatePublished - 1996
Externally publishedYes


  • Aggression
  • Serotonin
  • Tryptophan

ASJC Scopus subject areas

  • Pharmacology


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