How powerful is the placebo effect?
Jan. 3rd, 2008 10:38 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
drwexFor quite some time it's been well understood that the so-called "placebo effect" (*) can have statistically significant effects on self-reported metrics such as peoples' level of sadness/happiness, confidence, and so on. Roughly speaking, the placebo effect is about as powerful as antidepressant pills in all but the most depressed people, leading to a question of whether the pills are in fact doing anything at all.
But scientists have been slow to accept (and there hasn't been much evidence for) the placebo effect making a difference in objectively measured criteria. Like, say, the size of your hips. This morning an NPR story (http://www.npr.org/templates/story/story.php?storyId=17792517) pointed me to some research published last month (NY Times story here: http://www.nytimes.com/2007/12/09/magazine/09mindfulexercise.html?ref=magazine) by Harvard psychologist Ellen Langer that may push this idea further into the mainstream.
In this study, Langer and a student talked with hotel maids about their level of exercise. Despite being in jobs that kept them physically active all day and often involved quite demanding manual labor these maids didn't see themselves as "exercising." Two-thirds said they "didn't exercise."
Langer then measured externally visible metrics of physical health: BP, waist-to-hip ratios, etc. Then they educated about half the maids on the amount of exercise they were getting simply by performing their normal daily jobs. The other half got no education.
One month later Langer re-measured the same physical metrics and found that for at least three of the metrics there was a statistically significant change. The women who were told they were exercising showed the kids of physical improvements you'd expect from a comprehensive exercise program.
Unfortunately, the study doesn't appear to be air-tight. It's quite possible that the educated group of maids did things differently; perhaps they were more mindful about things like their diet, etc. The placebo effect might not be the thing responsible for the observed changes. But it might. Even if it doesn't account for all of the change, it may well account for some. Fascinating.
Neither story tells me where the research was published, but it did lead me to discover that Professor Langer has published a couple of pop-science books on the topic, and I'm ordering those. I'll write more once I've read them.
(*) The term is accurate but some people view it as a pejorative in the sense of "it's all in your head - you're making it up." Really that's not what's meant. The effect is real and measurable. I'm not intending anything pejorative here.
But scientists have been slow to accept (and there hasn't been much evidence for) the placebo effect making a difference in objectively measured criteria. Like, say, the size of your hips. This morning an NPR story (http://www.npr.org/templates/story/story.php?storyId=17792517) pointed me to some research published last month (NY Times story here: http://www.nytimes.com/2007/12/09/magazine/09mindfulexercise.html?ref=magazine) by Harvard psychologist Ellen Langer that may push this idea further into the mainstream.
In this study, Langer and a student talked with hotel maids about their level of exercise. Despite being in jobs that kept them physically active all day and often involved quite demanding manual labor these maids didn't see themselves as "exercising." Two-thirds said they "didn't exercise."
Langer then measured externally visible metrics of physical health: BP, waist-to-hip ratios, etc. Then they educated about half the maids on the amount of exercise they were getting simply by performing their normal daily jobs. The other half got no education.
One month later Langer re-measured the same physical metrics and found that for at least three of the metrics there was a statistically significant change. The women who were told they were exercising showed the kids of physical improvements you'd expect from a comprehensive exercise program.
Unfortunately, the study doesn't appear to be air-tight. It's quite possible that the educated group of maids did things differently; perhaps they were more mindful about things like their diet, etc. The placebo effect might not be the thing responsible for the observed changes. But it might. Even if it doesn't account for all of the change, it may well account for some. Fascinating.
Neither story tells me where the research was published, but it did lead me to discover that Professor Langer has published a couple of pop-science books on the topic, and I'm ordering those. I'll write more once I've read them.
(*) The term is accurate but some people view it as a pejorative in the sense of "it's all in your head - you're making it up." Really that's not what's meant. The effect is real and measurable. I'm not intending anything pejorative here.
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no subject
Date: 2008-01-04 03:09 pm (UTC)no subject
Date: 2008-01-04 06:14 pm (UTC)As I understand it (and I take your point that one ought to read the real published research, if there is any) the experiment showed a change in a population and attributed that change to one factor: education and change of viewpoint. If in fact the change was due to something else, that's a confounded experiment design and requires the experiment to be rerun with tighter controls (which I'd support anyway on the theory that reproduced results are better than a one-off).
no subject
Date: 2008-01-04 08:37 pm (UTC)of course, behind every factor there is a mechanism (incl. in placebogenesis, which we are finally beginning to understand via mri). if educated people attend more to their diets, then that's a mechanism, but it does not change the education's status as a factor.
and of course all science has to be reproducible. the standard p-value is >.05 cutoff, which is to say that one in twenty publishable results is purely coincidental.