PainSci notes on Vachon-Presseau 2018:
This trial claims to have found evidence of psychological and neurological traits that predict the potency and duration of placebo response. It’s garbage, a terrible study and a terrible paper. It seems to bizarrely prides itself on using a no-treatment group when this is clearly a poor choice, highly subject to a “frustrebo” effect. It is far too small a study, to underpowered, to actually detect a correlation between such squishy things as psychological traits and placebo response. The authors exhibit an egregious placebo-hype bias in their public statements and in the paper itself, and their methodology has a huge amount of “wiggle room” for p-hacking and rampant methodological flexibility. And there’s more.
Dr. James Coyne criticized the paper thoroughly and harshly for ScienceBasedMedicine.org. See: Debunking the magical power of the placebo effect for chronic pain (yet again).
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.
The placebo response is universally observed in clinical trials of pain treatments, yet the individual characteristics rendering a patient a 'placebo responder' remain unclear. Here, in chronic back pain patients, we demonstrate using MRI and fMRI that the response to placebo 'analgesic' pills depends on brain structure and function. Subcortical limbic volume asymmetry, sensorimotor cortical thickness, and functional coupling of prefrontal regions, anterior cingulate, and periaqueductal gray were predictive of response. These neural traits were present before exposure to the pill and most remained stable across treatment and washout periods. Further, psychological traits, including interoceptive awareness and openness, were also predictive of the magnitude of response. These results shed light on psychological, neuroanatomical, and neurophysiological principles determining placebo response in RCTs in chronic pain patients, and they suggest that the long-term beneficial effects of placebo, as observed in clinical settings, are partially predictable.
Specifically regarding Vachon-Presseau 2018:
- “Debunking the magical power of the placebo effect for chronic pain (yet again),” James Coyne, Sciencebasedmedicine.org.
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:
- The CANBACK trial: a randomised, controlled clinical trial of oral cannabidiol for people presenting to the emergency department with acute low back pain. Bebee 2021 Med J Aust.
- Relationships Between Sleep Quality and Pain-Related Factors for People with Chronic Low Back Pain: Tests of Reciprocal and Time of Day Effects. Gerhart 2017 Ann Behav Med.
- Modulation in the elastic properties of gastrocnemius muscle heads in individuals with plantar fasciitis and its relationship with pain. Zhou 2020 Sci Rep.
- Association Between Plantar Fasciitis and Isolated Gastrocnemius Tightness. Nakale 2018 Foot Ankle Int.
- A Bayesian model-averaged meta-analysis of the power pose effect with informed and default priors: the case of felt power. Gronau 2017 Comprehensive Results in Social Psychology.