Tuesday, May 4, 2010

Mind Over Matter

If you don't know about the placebo effect, this bit from an article by Olivia Judson in the NY Times is a good introduction:
First, what is the placebo effect?

It’s the improvement in health that some patients experience because of the feeling that they are receiving medical care. A classic example comes from drug trials. Suppose patients are randomly divided into three groups: those who get no treatment, those who get the drug that’s being tested, and those who get the placebo treatment — typically a pill that looks and tastes like the drug, but doesn’t contain it, or any other active ingredient.

The idea is that the “no treatment” group shows how many people would have gotten better by themselves; the “placebo” group shows any effect of participating in medical rituals (like taking pills); the “drug” group shows any effect of the drug over and above the effect of medical rituals. Simple.

Or not. Different studies of the placebo effect report wildly different results. One survey of 117 trials of two ulcer drugs found that, depending on the trial, patients in the placebo group had anywhere from zero to a 100 percent recovery rate.

The drugs also varied in their effectiveness from one trial to the next; sometimes patients on the placebo did better than those on the drug. Intriguingly, the results varied from country to country, with Brazilians showing no placebo effect and Germans having a strong one. Why? No one knows, but it doesn’t appear to be because of anything inherently German: trials of drugs for hypertension found a weaker placebo effect in Germany than in other countries.
To have results where the placebo performs better than the drug is shocking (assuming the drug has some efficacy and isn't in fact helping to cause the problem). The variability shows how difficult it is to do any experiments with humans. They are just too complex, too unpredictable except for the simplest & shortest of tests. But that's what makes being a human and a participant in human society so much fun. Surprises all the time!

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