Acute tryptophan depletion as a model of depressive relapse: behavioural specificity and ethical considerations

Acute tryptophan depletion transiently induces symptoms in those with remitted depression. The behavioural specificity is uncertain, however. Recently, symptom provocation studies have become controversial, particularly in the USA.

To assess the specificity of acute tryptophan depletion. To investigate systematically the subjective experiences of those taking part in a symptom provocation study.

Twenty individuals with remitted depression underwent acute tryptophan depletion in a double-blind, crossover trial. Psychiatric symptoms and self-schemata relevant to depression were assessed. The quality of the informed consent procedure and subjective experiences were also evaluated.

Acute tryptophan depletion induced a specific depressive response. The effects were more pronounced in females than in males. Participants were quite satisfied with the informed consent procedure. They had understood that this was a fundamental research project and personal benefits were not expected. However, some participants still found it a positive experience.

Acute tryptophan depletion is a suitable model of vulnerability to depression, from both a scientific and an ethical perspective.