One article on PainSci cites Locher 2017: Placebo Power Hype
PainSci notes on Locher 2017:
A couple of scientific papers (eg Kaptchuk) have suggested that deception isn’t necessary for a placebo to work. That is, they may be effective even when people know that they are placebo. However, this study challenges that hypothesis by demonstrating that deceptive placebo only work if you replace the deception with some other reason for the patient to have faith in it.
They compared four groups of about 40 patients each, with one (control) group getting nothing at all, and the other three all receiving a placebo cream presented in a different way:
- a deceptive placebo: “this cream is medicine”
- open-label without rationale: “this cream is a placebo”
- open-label with rationale: “this cream is placebo, but it will help you, because placebo is potent”
Subjects were tested for heat-pain tolerance. By objective measures, everyone was the same, but there were differences when measured subjectively. Groups 1 and 3 were both given a reason to believe the cream would work, and they both experienced the same reduced intensity and unpleasantness; group 2 got no benefit. Thus the authors conclude that “placebos with a plausible rationale are more effective than without a rationale.” Translation: expectation of efficacy is the active ingredient, whether it is achieved with deception or exaggeration of the power of placebo.
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
Research on open-label placebos questions whether deception is a necessary characteristic of placebo effects. Yet, comparisons between open-label and deceptive placebos (DPs) are lacking. We therefore assessed effects of open-label placebos and DPs in comparison with no treatment (NT) with a standardized experimental heat pain paradigm in a randomized controlled trial in healthy participants. Participants (N = 160) were randomly assigned to NT, open-label placebo without rationale (OPR-), open-label placebo with rationale (OPR), and DP. We conducted baseline and posttreatment measurements of heat pain threshold and tolerance. Apart from the NT, all groups received an application of a placebo cream. Primary outcomes were planned comparisons of heat pain tolerance and the corresponding intensity and unpleasantness ratings. Objective posttreatment pain tolerance did not differ among groups. However, for subjective heat pain ratings at the posttreatment tolerance level, groups with a rationale (OPR and DP) reported diminished heat pain intensity (t(146) = -2.15, P = 0.033, d = 0.43) and unpleasantness ratings (t(146) = -2.43, P = 0.016, d = 0.49) compared with the OPR- group. Interestingly, the OPR and the DP groups did not significantly differ in heat pain intensity (t(146) = -1.10, P = 0.272) or unpleasantness ratings (t(146) = -0.05, P = 0.961) at the posttreatment tolerance level. Our findings reveal that placebos with a plausible rationale are more effective than without a rationale. Even more, open-label placebos did not significantly differ in their effects from DPs. Therefore, we question the ubiquitously assumed necessity of concealment in placebo administration.
- “Placebos without deception: a randomized controlled trial in irritable bowel syndrome,” Ted J Kaptchuk, Elizabeth Friedlander, John M Kelley, M Norma Sanchez, Efi Kokkotou, Joyce P Singer, Magda Kowalczykowski, Franklin G Miller, Irving Kirsch, and Anthony J Lembo, PLoS ONE, 2010.
- “Open-label placebo treatment in chronic low back pain: a randomized controlled trial,” Cláudia Carvalho, Joaquim Machado Caetano, Lidia Cunha, Paula Rebouta, Ted J Kaptchuk, and Irving Kirsch, Pain, 2016.
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Association of Lumbar MRI Findings with Current and Future Back Pain in a Population-based Cohort Study. Kasch 2022 Spine (Phila Pa 1976).
- A double-blinded randomised controlled study of the value of sequential intravenous and oral magnesium therapy in patients with chronic low back pain with a neuropathic component. Yousef 2013 Anaesthesia.
- Is Neck Posture Subgroup in Late Adolescence a Risk Factor for Persistent Neck Pain in Young Adults? A Prospective Study. Richards 2021 Phys Ther.
- Sudden amnesia resulting in pain relief: the relationship between memory and pain. Choi 2007 Pain.
- Photobiomodulation therapy is not better than placebo in patients with chronic nonspecific low back pain: a randomised placebo-controlled trial. Guimarães 2021 Pain.