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

ABSTRACT

BACKGROUND: 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. AIMS: To assess the specificity of acute tryptophan depletion. To investigate systematically the subjective experiences of those taking part in a symptom provocation study. METHOD: 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. RESULTS: 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. CONCLUSIONS: Acute tryptophan depletion is a suitable model of vulnerability to depression, from both a scientific and an ethical perspective.