Deception isn’t necessary for placebo, but it does need some kind of story
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.
related content
- “Placebos without deception: a randomized controlled trial in irritable bowel syndrome,” Kaptchuk et al, PLoS ONE, 2010.
- “Open-label placebo treatment in chronic low back pain: a randomized controlled trial,” Carvalho et al, 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:
- Inciting events associated with lumbar disc herniation. Suri 2010 Spine J.
- Prediction of an extruded fragment in lumbar disc patients from clinical presentations. Pople 1994 Spine (Phila Pa 1976).
- Characteristics of patients with low back and leg pain seeking treatment in primary care: baseline results from the ATLAS cohort study. Konstantinou 2015 BMC Musculoskelet Disord.
- Effectiveness and cost-effectiveness of universal school-based mindfulness training compared with normal school provision in reducing risk of mental health problems and promoting well-being in adolescence: the MYRIAD cluster randomised controlled trial. Kuyken 2022 Evid Based Ment Health.
- No long-term effects after a three-week open-label placebo treatment for chronic low back pain: a three-year follow-up of a randomized controlled trial. Kleine-Borgmann 2022 Pain.