On the growing effectiveness of placebos

from NPR’s Morning Edition: http://tiny.cc/LI6rn
Quote: it turns out the placebo effect might not be as stable as we’ve assumed. Barsky recently published a study that looked at a bunch of antidepressant trials that had taken place between 1980 and 2005, and he found that in 2005 patients in these trials responded to placebos way more than patients did back in the 1980s.”The placebo response was about twice as powerful than it was in the 1980s,” Barsky says. “That’s a pretty significant difference.”

In other words, placebos seemed to be twice as powerful as they were 30 years ago.

No one, including Barsky, really knows why the placebo effect appears to be changing. But Ted Kaptchuk, another Harvard professor who studies the placebo effect, says that placebo “drift” as it’s now known, appears to be real. He says it’s shown up in more than just antidepressant trials. And one possible explanation, according to Kaptchuk, is that there’s been a change in our expectations.

For example, Kaptchuk points out that by 2005 our belief in the power of antidepressant drugs was very strong, and that might account for the shift. “There’s a lot of confidence, and that changes both providers impression of what happened, and presumably the patient’s experience of what could happen.”

But also, says Kaptchuk, it could be that because drug companies mostly pay for drug experiments, doctors who do the research have a subtle incentive to say the drugs are working. And since doctors don’t know who’s taking a real pill and who’s not, the fact that they see benefits in all patients would also inflate the placebo effect.

Then there’s another possible explanation.

Researchers, especially in pharmaceutical trials, get paid for every patient they recruit. But often, Kaptchuk says, it’s hard to find people, so doctors will sometimes admit patients to trials who simply aren’t that depressed. And typically, he says, people who aren’t that depressed are much more susceptible to the placebo effect.

“I don’t think there’s out-and-out fraud,” says Kaptchuk. “I think that you’re under pressure to recruit. It’s really hard to recruit people. And you know, (when) it’s borderline, (you) put them in. And those people on the borderline at the end, they are better in the placebo group.”

Whatever the cause, placebo drift is something that has the potential to cause real mischief in medical trials.” for more: http://tiny.cc/LI6rn


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