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Warning about side effects can increase their occurrence: an experimental model using placebo treatment for sleep
Ben Colagiuri1, Kari McGuinness, Robert A Boakes
1School of Psychology, University of Sydney, Sydney, NSW, Australia. ben.colagiuri@sydney.edu.au
Journal of Psychopharmacology (Oxford, England)
|September 21, 2012
Summary
Warnings about potential side effects can cause placebo-induced side effects. Participants warned about fewer bogus side effects reported experiencing them more often, suggesting expectation influences adverse event reporting.
Area of Science:
- Psychology
- Clinical Trials
- Pharmacology
Background:
- Patient and clinical trial participant warnings about potential adverse effects are standard practice.
- These warnings may inadvertently create expectations, leading to placebo-induced side effects.
Purpose of the Study:
- To investigate whether warnings about potential side effects can lead to placebo-induced side effects.
- To examine the influence of the number of warned side effects on their occurrence.
Main Methods:
- An experimental model using undergraduates with sleep difficulties was employed.
- Participants received placebo treatment disguised as a hypnotic for one week.
- Groups were warned about either one or four bogus side effects.
Main Results:
- Placebo treatment significantly improved sleep difficulty compared to a no-treatment control group.
- Participants warned about one side effect showed better recall of that effect than those warned about four.
- A trend indicated participants were more likely to report experiencing a warned side effect, especially when warned about only one.
Conclusions:
- Evidence suggests that warnings about potential side effects can indeed induce their occurrence.
- The number of warned side effects may influence the likelihood of reporting placebo-induced effects.
- Consideration of placebo-induced side effects is crucial when interpreting clinical trial data on adverse events.
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