Often, when you publish something in a reasonably posh journal, your mates write you a little email to say congratulations. However, if you write a word like ‘daft’ in an article that is published in a posh journal like BMJ, it is not just your mates who say congratulations! I got about 40 emails from people I have never heard of over this one. What, exactly, drew such a word out of me? Well it is idea of the placebo being a mysterious, almost magical thing that just happens sometimes. I wrote the letter in response to another paper showing that there are therapeutic effects NOT explained by a particular drug, or technique. People often talk about this magic figure of 30% that quantifies the proportion of people who respond to placebo pain relievers and then extend it to say that 30% of people respond to, well, nothing. I reckon that if you don’t respond to something that you THINK is a painkiller, then you are either dead, or you have never known the thing you think is a painkiller to actually relieve pain. To say that the only thing that can relieve pain in a therapeutic encounter is the molecule in the pill is, frankly, daft. As I always say, the smart brain would respond to anything that is relevant to the perception of threat to body tissue. Anyway, read the letter…..
G Lorimer Moseley, Nuffield medical research fellow
University of Oxford, Oxford OX1 3QX
The notion that placebo responses are responses that are evoked by nothing is nonsense. The study by Kaptchuk et al and the study by Waber et al in JAMA illustrate clearly that the “placebo”’ responses observed are in fact responses to things other than the thing to which we hypothesise a response. Therefore, placebo responses reflect the limitations of our experimental design, our appreciation of the contributors to a patient’s symptoms, and our appreciation of what might change those underpinning factors. The convincing placebo data concern symptoms—experiences reported by patients. That means that symptoms are outputs of the brain. That a placebo response occurs means that something has changed the brain’s evaluation of whether or not to evoke that symptom. This makes a placebo response not a response to nothing, but to something we haven’t identified or measured. Take pain for example: it emerges according to an implicit evaluation of . . .
See full article at British Medical Journal 336:1086
1. Kaptchuk TJ et al, Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome (2008), BMJ;336:999-1003
Moseley GL (2008). Placebo effect: Reconceptualising placebo. BMJ (Clinical research ed.), 336 (7653) PMID: 18483023