This one might be a new one for you: the Nocebo Effect, on today's Moment of Science.
I'm sure many of you've heard of the placebo effect, but today we're going to talk about the nocebo effect. The nocebo effect, in a sense, is the opposite of the placebo effect. If the placebo effect means you feel better just because you believe a certain treatment is going to work, then the nocebo effect means that you feel worse just because you expect the worst.
For example, in one study, some patients were warned that taking aspirin may cause gastro-intestinal side-effects while others weren't. Those patients who were warned about potential side-effects were three times more likely to report discomfort than those patients who weren't warned, although the incidence of actual stomach damage was the same for both groups.
The nocebo effect is different from ordinary pessimism--it's more like a self- fulfilling prophecy. If you believe something will go wrong, that belief might just cause it to go wrong. The classic example of this is people who go into surgery absolutely convinced that they're going to die; very few of them actually end up surviving.
Y: Keep in mind though that there hasn't been much research on the nocebo effect, partly because it isn't ethical to induce illness in people who aren't sick. Still, drug side-effects end up costing the healthcare system about seventy-six billion dollars a year, and if even a small percentage of these are psychosomatic rather than biological, the nocebo effect is worth investigating.