Something out of nothing: the placebo effect

Aaron Vallance is currently a staff-grade child and adolescent psychiatrist with the Service for Adolescents and Families in Enfield (Charles Babbage House, 1 Orton Grove, Enfield EN1 4TU, UK. Email: aaronvallance{at}doctors.org.uk). He is also Associate Research Fellow with the Metabolic and Clinical Trials Unit, Department of Mental Health Sciences, The Royal Free Hospital, London, and a member of the Editorial Board of the Journal of Alternative and Complementary Medicine.

The history of the concept of the placebo effect and research into its quantification and mechanisms are reviewed, particularly in relation to psychiatry. Research has demonstrated a notable placebo effect in depression: a large proportion of the clinical effect of antidepressant medication is attributable to the effect. Various mechanisms have been hypothesised: anxiety relief, expectation, transference, ‘meaning effects’ and conditioning. Recent research from neuroimaging has unveiled that the effect is associated with biological correlates in the brain. Despite the renewal of research into the placebo effect, many questions remain unanswered. This partly reflects philosophical obstacles such as the mind/body dichotomy, which are inherent in conceptualising the effect. However, it also demonstrates the vast scope for further research into this area. Ultimately, an understanding of the processes that underlie the placebo effect should allow a rationalised therapeutic approach to be developed to maximise the clinical benefit of the therapeutic encounter.

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