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Placebo Effects Revisited (sciencebasedmedicine.org)
25 points by tokenadult on Mar 24, 2010 | hide | past | web | favorite | 9 comments



As far as I'm aware, a physiological response to a placebo (and corresponding nocebo) was a well-documented effect. Some examples:

* Heart-rate (not sure what else?) being equally affected by decaf and regular coffee

* Impaired cognitive effects from drinking far too soon after initial drinking (and as measured by BAC)

* Reduced stress hormones when arm is placed in an ice bucket after taking a placebo and being told it's morphine

* Physical nausea including vomiting after being told potential side effects of a trial "drug"

In terms of the body "healing" itself, I can see how the placebo effect could be attributed to other things.


a well-documented effect

I just did some of the obvious Google Scholar searches on some of the issues you mention, but I'm not seeing clear statements of these findings being well documented in a publication that is not behind a paywall for me. Do you have citations at hand?


Try pubmed directly rather than Google Scholar. Most examples I'm quoting are articles I've read in New Scientist so if you have a subscription you can check their article history. I promise I'm not making them up.


tl;dr: Some people named Hróbjartsson and Gøtzsche did a meta analysis on clinical trials suggesting that the placebo effect is solely a reflection of bias or rigor in the given experiment, not of some physiological, "mind over matter" phenomenon.


More particularly, from the submitted article, "There is no measurable physiological benefit from placebo interventions for any objective outcome. There is a measured benefit for some subjective outcomes (mostly pain, nausea, asthma, and phobias), but the wide variation in effect size suggests this is due to trial design (and therefore bias) rather than a real effect." In my words, it might be expected that one would see a placebo effect if the clinical records are based on patient self-reports of, e.g., pain or nasal congestion, but a placebo effect would be quite astounding if they were statistically significant over multiple double-blind trials in detection of a chemical in a blood test.


Do patterns of brain activation not count as an "objective" difference to them? The effects of many placebos are clearly visible on MRI.


What are some examples in peer-reviewed literature for which you have citations at hand?


This is a recent one from Science that got a good amount of press when it came out: http://www.sciencemag.org/cgi/content/abstract/326/5951/404


Thank you for that reference. That led me by hyperlink to this

http://brain.oxfordjournals.org/cgi/content/full/awq019v1

and the link here draws a distinction that I think is important, the distinction between injury and pain. The paradox of pain, as this article says, is that patients with severe injury have little pain, while other patients with possibly no injury at all have severe pain. Granting that sham treatments (placebos) can reduce patient perception of pain, how do we establish that they produce more healing of injury, more consistently, than the passage of time as the body's evolutionarily selected healing mechanisms work?




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