Introduction: This paper focuses on the methodology and behavioural results of the tryptophan depletion challenge.
Methods: A Medline search (1985-2002) using the keywords 'tryptophan depletion' and 'mood' has been performed.
Results: Rapid depletion is obtained by morning intake under fasting condition of a tryptophan-free amino-acid mixture. Subjects with a family history of mood disorders and depressed patients receiving serotoninergic drugs demonstrate a mood-lowering effect. However, these effects are limited or absent in normal volunteers and naive depressed patients.
Conclusion: The tryptophan depletion challenge has largely contributed to the understanding of the physiopathology of depression. However, the mood response to acute tryptophan depletion challenge in healthy volunteers is not as sensitive as a 'depression model'.