Acute tryptophan depletion. Part I: rationale and methodology.
OBJECTIVE
Acute tryptophan depletion (ATD) is an experimental technique that has been widely used over the last decade to investigate the role of serotonin (5-HT) in a variety of disorders. This review, the first of two articles, describes the rationale behind this technique and provides detail on how it is applied in research settings.


METHODS
The authors outline the development of this technique with reference to the seminal literature and more recent findings from neuroimaging and neuroendocrine studies. This is supplemented by the authors' clinical experience of over 5 years of continuous experimental work with this paradigm in over 50 subjects.


RESULTS
Acute tryptophan depletion is a method that significantly reduces central 5-HT in human subjects. Non-serotonergic explanations of the effects of ATD have not been confirmed, supporting the specificity of this method.


CONCLUSIONS
The ATD technique is a valid method of manipulating central 5-HT levels. The second article in this series will review the application of ATD in depression, anxiety and other psychiatric conditions.
Hood
Sean D
SD
Psychopharmacology Unit, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, England, UK.
Bell
Caroline J
CJ
Nutt
David J
DJ
D001812:Blood-Brain Barrier; D006801:Humans; D001523:Mental Disorders / Q000378:metabolism* / Q000503:physiopathology*; D012701:Serotonin / Q000502:physiology*; D014364:Tryptophan / Q000172:deficiency*
D012701:Serotonin; D014364:Tryptophan