Everyone is familiar with the placebo and nocebo effects – when the expectation of benefit or harm produces positive or negative effects, respectively. Impressively, however, the power of such effects can be modulated on another level by incorporating cost into the placebo effect.
This fascinating little study tested the effect of two different placebo medications on motor and brain activation in patients suffering from Parkinson’s disease. Initially, each patient received motor and fMRI testing before and after levodopa administration. Then, on a subsequent visit, patients received subcutaneous injections of saline 4 hours apart – with participants being told each was the same novel dopamine antagonist, one of which was manufactured using a “cheap” manufacturing process and one using an “expensive” process. Each participant again received motor and fMRI testing following each injection.
As somewhat expected, each placebo injection produced some improvement in motor function – with the effect reaching statistical significance and almost 30% improvement from baseline for the “expensive” placebo. Even more impressive, the “expensive” placebo was not too far off the effects of levodopa, which produced approximately a 50% improvement in motor symptoms from baseline. Most entertainingly, however, the placebo effects were even present on fMRI imaging. The “expensive” placebo showed brain activation levels similar to levodopa, while the “cheap” placebo had a differing distribution of activity apparently consistent with increased effort.
Yet again, the very real power of placebo – with its magnitude of effect tied to expectations related to cost!
“Placebo effect of medication cost in Parkinson disease”
http://www.ncbi.nlm.nih.gov/pubmed/25632091