Tuesday, June 13, 2006

Doggerel #14: "It Works THROUGH the Placebo Effect!"

Welcome back to "Doggerel," where I ramble on about words and phrases that are misused, abused, or just plain meaningless.

One of the funniest arguments I've heard from woos is that their magic pills work through the placebo effect, and I don't think they mean it in a Zen "acting by not acting" sort of way.

The placebo effect is what you get when you do nothing, but think you're doing something: It's a combination of two things: Psychological tricks and coincidental recovery.

First, are the psychological tricks: Confirmation bias, the regressive fallacy, misattribution, subjective validation, and so on and so forth: We essentially fool ourselves into thinking the symptoms aren't as bad, or not as common, etcetera. They're still there, but we have an excuse to ignore them: They don't fit with expectations, so we rationalize them away. There's no "power of positive thinking" going on, just a conscious and unconscious motivation to ignore what doesn't fit. This is why double-blinding is important: It make most of those rationalizations very implausible, and points of view irrelevant: Belief isn't going to change the numbers.

Second, there is the physical aspect: Natural improvement and coincidental recovery. It could be that a person's immune system is rallying for a final assault when he takes the treatment. There's no way to be certain that it's the drug that's doing anything. That's where the placebo control in studies comes in: Compare the drug to essentially doing nothing as a base line. If there's a significant difference between the placebo group and the treatment group, it's unlikely to be coincidence. The bigger the study, the less likely coincidences become.

There are probably more aspects to placebos and nocebos, but that should be the bulk of it: The placebo effect is what happens when you merely think you're doing something.


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Anonymous said...

Placebos have also been shown to elicit measurable physiological changes in excess of the untreated control (e.g. Sauro and Greenberg, J Psychosom Res 58, 115-120). The typical explanation that I've heard for this is a semi-classical conditioning--the patient is conditioned to have a physiological response upon taking a drug, and this conditioning itself causes the measured changes. I think that this is an important factor to consider in any discussion of placebo effect.

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beepbeepitsme said...

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Anonymous said...

I don't see the problem in the placebo effect having physiological effects - after all thoughts are part of the nervous system and the nervous,endocrine and immunological system are all intimately connected.
Isn't the reason that medical studies often have a treatment, no treatment and placebo group to account for the possible physiological impact of the placebo effect?

Bronze Dog said...

I don't really have a problem with there being some physiological effects being included with placebo. To my knowledge, though, they tend to be limited, if at all present.

daedalus2u said...

The placebo effect is real, and is mediated through nitric oxide.

I have posted quite an extensive blog on the physiology behind the placebo effect.

What it does is switch physiology from the "fight or flight" state to the "rest and relaxation" state.

Physiology is so well evolved that resources are allocated quite precisely. When you need to "run from a bear", your body doesn't waste ATP and other resources on repairing damage that will be moot if the bear catches you. But if the "fight or flight" state persists, there is less repair and healing.

Bronze Dog said...

Now that is both cool and reasonable-sounding. I may have to read your post and update this entry sometime. If you're interested in guest-posting an update like Infophile did for "Quantum," just leave me another comment or drop something in my gmail.

Joshua Zucker said...

I think what they mean is that their woo is the CAUSE of the placebo effect, or the MECHANISM, or something like that.

There's been a flurry of research lately on exactly those questions, though -- exactly what biochemical pathways are involved in the placebo effect? -- so I think they may be out of luck with those claims soon, too.