Perception of cost influences the placebo effect
The takeawayThe perception of a medication’s cost may enhance the placebo effect, which occurs when a person takes a nonactive substance that they believe is medicine (such as a sugar pill or saline) and experience a temporary effect.
Why is it important?The placebo effect is particularly strong in people with Parkinson’s, thanks in part to the involvement of dopamine in both the effect and the disease. As a result, placebo effects can interfere with clinical trial results, making it difficult to determine whether a beneficial result is due to the experimental drug or to the effect itself.
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Impact opinion“The placebo effect is profound in Parkinson’s disease and presents a challenge whenever performing clinical trials. The more we learn about factors that govern the placebo effect, the better we can design trials aimed at slowing Parkinson’s progression.” Dr. Patrik Brundin
BackgroundClinical trials are an important step in translating a lab finding into patient care, and involve several stages that test the safety and effectiveness of the therapy. One common type of trial is called a double-blind trial, in which one group of patients is given the real drug and the other is given a placebo, which looks like the drug but contains no medication. In double-blind trials, neither the patients nor the physicians know which group is which, although they do know that both the medication and the placebo will be used. This model is designed to allow researchers to compare the effect of the actual drug against a control group without the expectations of the patients or physicians muddying the results.
Sometimes, however, patients taking the placebo believe they are taking the real drug and, as a result, experience beneficial results. This placebo effect can interfere with clinical trial results.
The detailsResearchers took the study of the placebo effect a step farther by investigating how the perception of cost impacts the strength of the effect. Put simply, do people expect a more expensive medication to work better than a cheaper one? And, if so, how does this impact the placebo effect?
To answer these questions, patients were given levodopa, the gold standard for Parkinson’s treatment, followed by two saline injections. They were then told that the injections contained two medications—one that cost $100 and one that cost $1,500. Their responses were measured in several ways, including evaluation on the Unified Parkinson’s Disease Rating Scale. The score for the expensive placebo ranked 10 percent higher than that of the cheaper placebo, although the effect of levodopa was stronger than either placebo.
However, when given a learning task (that was monitored by brain imaging) patients who took the cheap placebo first had more brain activation in certain regions than did people who took the expensive placebo.
Other things to know
- It appears the order in which the placebos were given (“cheap” then “expensive” vs. “expensive” then “cheap”) had an impact on the results.
- In an editorial on the article, the authors note that knowing whether the patients considered the $100 placebo “cheap” would be helpful.
The editorial authors also raise the point of patient trust as the study involved an element of deception (the study complied with federal regulations) and urged researchers who undertake future experiments to add additional patient protections.