17 January, 2010

The Nocebo Effect

We've all heard of the placebo effect, when sham treatments (sugar pills, toothpicks instead of acupuncture needles) are just as effective or indeed more effective than the real treatment being tested.  But how many of us know about the nocebo effect?  Did you know that placebos can cause side effects?  I surely didn't.
The best moment was Dr Peter Fisher from the (NHS-funded) Royal London Homeopathic hospital explaining that homeopathic sugar pills have physical side-effects – so they must be powerful.

Can a sugar pill have a side-effect? Interestingly, a paper published in the journal Pain next month looks at just this issue. It found every single placebo-controlled trial ever conducted on a migraine drug, and looked at the side-effects reported by the people in the control group, who received a dummy "placebo" sugar pill instead of the real drug. Not only were these side-effects common, they were also similar to those of whatever drug the patients thought they might be receiving.
Next time I experience some vague malaise while taking a treatment, I'll have to remember that the faint nausea, the headache, or what have you might actually be caused by my expectations, not the treatment itself.  Fascinating.

And the next time somebody babbles about how awesome homeopathy is, here's a useful tidbit for ye:
There were comedy highlights, as you might expect from any serious inquiry into an industry where sugar pills have healing powers conferred upon them by being shaken with one drop of the ingredient which has been diluted so extremely that it equates to one molecule of the substance in a sphere of water whose diameter is roughly the distance from the Earth to the sun.

Ben Goldacre's whole article is worth reading.  As are all his others.  Definitely don't miss the possible role of aliens in siting Woolworth's stores.  Bad science has never been so good!

(Tip o' the shot glass to Matthew Cobb, who's doing a stellar job filling in for Jerry Coyne)


WeeDram said...

It's ALL about the mind, baby. ;)

This flu season I convinced a co-worker to get both flu shots; he had been hesitant because he thought he would catch the flu from the vaccines.

When I explained the vaccines contained KILLED virus, and it was impossible to get the flu from receiving the shots he went ahead and got in line.

Sure enough, next day he said he wasn't feeling great, had had some sort of reaction. I'm pretty damn sure it was "psychosomatic", even though I told him that yeah, some people could have a bit of a reaction to one or more of the components.

Cujo359 said...

A body still generates antibodies to fight the vaccine, just like it would a disease. Feeling less than optimal for a day isn't out of the question. The CDC has a page devoted to possible reactions to the vaccine. They sound pretty generic, really.