August 27, 2005
Placebo effect and views on the mind
The Economist has a short article on how researchers have observed that people's brains emit more endorphins when given a placebo and told it will counteract pain. The article starts with this:
The placebo effect, long considered nothing more than psychological suggestibility, does now appear to be genuine.
It's hard for me to imagine the worldview necessary for that sentence to make any sense. If you believe (as I do) that the mind is fully implemented by our biology then you wouldn't at all be surprised that there's a biological cause for the observed decrease in subjective pain. On the other hand, if you still put Descartes before the horse and believe in a kind of soul or other mind/body dualism then the idea that a non-physical "psychological suggestibility" isn't genuine (even though it stops the equally non-physical pain) is ludicrous.
It seems to me that The Economist and probably a majority of Westerners want to walk a middle road, accepting only the physical, observable, and scientific world as "genuine" while at the same time refusing to accept that a direct corollary of that belief is that our own minds must be a part of that physical, observable world. It's no wonder we have such difficulty dealing with issues like mental illness in this culture...
Posted by bug to Mind and Brain at August 27, 2005 12:03 AM | TrackBackWhat I find strange about the sentence is that it seems to imply that somehow this new development changes the respect the scientific community has for the placebo effect. I can't speak for the "scientific community" as a whole, but it seems to me that the placebo effect has a great deal of respect for it, otherwise, why put such a huge emphasis on double blind studies?
Moreover, study after study after study has shown that mental state has an effect on health. Placebo surgery even seems to work, and I recall reading about one study where 100% of the placebo group showed improvement while 90% (or so) of the group who got the actual surgery being tested improved.
What is noteworthy about this study, though, is that is shows that the suggested mind is actually changing the body, rather than its perception of the body (an alternate hypothesis is that there is no testable difference in the bodies of people getting placebos, but that they report less pain because their perception is altered). I think this hypothesis has a lot of evidence in earlier studies, though.
I gather there've been some questions raised about the placebo effect in the past 5 years, spurred on by an article published in the 2001 New England Journal of Medicine which surveyed 114 placebo-using medical studies and found little evidence that placebos had any powerful clinical effects.
Dylan Evans' recent book Placebo: The Belief Effect (sumarized in this short paper) argues that the reason for the discrpancy is that the placebo effect only helps with some kinds of conditions — namely pain, swelling, stomach ulcers, depression, and anxiety — and that by lumping everything into one average the meta-study washes out the few places where placebos actually work. He also suggests that placebos probably work by triggering the release of endorphins — looks like he hit the nail on the head on that one.
As for the philosophical implications of the study, you're right that it associates the placebo effect directly with endorphins rather than with some (presumably much less easy to identify) higher-level interpretation mechanism. I suppose in a way the simple explanation found here allows us to avoid the whole question of "is the part my brain being fooled a part I want to consider genuine" for now...
Posted by: Bug at August 28, 2005 12:14 AM