Reverse Placebo Effect


A though about medicine.

You hear a lot about the placebo effect. From what I can tell, its pretty powerful. So I was wondering if there is a reverse placebo effect. This would mean you took some medicine that normally works, but it didn't because you thought it wouldn't.

This leads a possible experiment: We get together a group of people for a medical study. However, instead of dividing them to 2 groups (medicine and placebo), we divide them into 4. First, we divide them in half, and tell half of them they are getting medicine and half they are getting a placebo. Then we give half of each group medicine and the other half of the group a placebo.

We don't tell them what we are doing. That might mess up the results. But we will need them to agree to be in the study, so we tell them we are comparing 3 groups: medicine, placebo-you-think-is-medicine, and placebo-you-know-is-placebo. We say we're doing this to see if placebo pills have any healing power of their own. It's an important test because, if they do, a whole lot of medical studies are probably wrong.

And that would be interesting. However, the really interesting comparison is between medicine-you-know-is-medicine and medicine-you-think-is-a-placebo. Does knowing it's medicine make it work better? Does it cause more side effects? If science is "rules about nature that work even if you don't believe them", does that mean medicine might not be scientific?

In a totally different direction, how does the placebo effect work anyway? Yes, I know that you believe something and it affects your health, but how? There has to be all sorts of biology between those two points. If we could somehow get access to those processes artificially, we could probably cure all sorts of things.


I got the following useful response (by someone who knows a lot more about this stuff than me):
Hey Richard, thought this was a cool post! While I don't claim to know much, I think the neurobiology of the placebo effect is absolutely fascinating!! I think that a very crude explanation which ties many theories together is that it has a lot to do with the 'higher functioning' part of the brain tricking the lower more primitive parts of our brain into altering physiological function of the body via neurotransmitter modulation. That being said, a placebo effect in itself probably wouldn't cure many things, but has certainly proven time and time again to be a strong (albeit not exactly ethical) adjunct in medical therapies (proven by many many meta analyses!) The brain is fascinating, don't you think?

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