In medicine today, placebos serve a specific purpose. In the form of sugar pills or pretend treatments, placebos provide a benchmark against which researchers can compare drugs and other medical interventions.
Ted Kaptchuk is a professor at Harvard Medical School. He says it's often hard to pin down why a medical treatment has worked.
"If people get better, we want to know if it's because [of] the drug we gave them, or is it spontaneous remission, or is it because of the doctor-patient interaction, or is it because of the ritual of taking pills?" he says.
Placebos allow researchers to separate out those factors from the influence of the drug itself. They enable doctors to determine whether a treatment does what it's purported to do.
Outside the setting of a clinical trial, you're unlikely to find physicians dispensing placebos. The reasoning is simple. It's long been assumed that the placebo effect can only take place when patients don't know they're taking a placebo. In other words, when patients have been deceived. For many doctors, deception like this would violate their profession's ethics.
But recently, researchers like Ted Kaptchuk began to question whether our assumptions about placebos were valid.
"Everyone believed that deception or concealment is necessary for people to respond to placebo because the idea was, you fake people, you trick them. I sat with myself for a long time, read the literature and I said, 'You know what. No one's tested that ever in history. What's going on here?'"
This week on Hidden Brain, we consider what it means to be sick and what it means to heal, and the powerful tool that modern medicine has overlooked.
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"To What Extent Are Surgery And Invasive Procedures Effective Beyond A Placebo Response? A Systematic Review With Meta-analysis of Randomised, Sham Controlled Trials" by Wayne B. Jonas, Cindy Crawford et. al. in BMJ Open, 2015.
Credulity: A Cultural History of US Mesmerism by Emily Ogden, 2018.
"Components Of Placebo Effect: Randomized Controlled Trial In Patients With Irritable Bowel Syndrome" by Ted J. Kaptchuk, John M Kelly, et. al. in BMJ,2008.
"Placebos Without Deception: A Randomized Controlled Trial In Irritable Bowel Syndrome" by Ted Kaptchuk, Elizabeth Friedlander, et. al. in PLoS One, 2010.
"Open-Label Placebo Treatment for Cancer-Related Fatigue: A Randomized-Controlled Clinical Trial" by Teri W. Hoenemeyer, Ted J. Kaptchuk et. al. in Scientific Reports, 2018.
"Is The Placebo Powerless?" by Asbjørn Hróbjartsson and Peter C. Gøtzsche in The New England Journal of Medicine, 2001.
"Placebo Interventions For All Clinical Conditions" by Asbjørn Hróbjartsson and Peter C. Gøtzsche in Cochrane Database of Systematic Reviews, 2010.
Hidden Brain is hosted by Shankar Vedantam and produced by Jennifer Schmidt, Parth Shah, Rhaina Cohen, Laura Kwerel, and Thomas Lu. Our supervising producer is Tara Boyle. You can also follow us on Twitter @hiddenbrain, and listen for Hidden Brain stories on your local public radio station.