Harvard Magazine has an interesting look at the study of placebos – fake medical cures that should have no effect but often do.

Two weeks into Ted Kaptchuk’s first randomized clinical drug trial, nearly a third of his 270 subjects complained of awful side effects. All the patients had joined the study hoping to alleviate severe arm pain: carpal tunnel, tendinitis, chronic pain in the elbow, shoulder, wrist. In one part of the study, half the subjects received pain-reducing pills; the others were offered acupuncture treatments. And in both cases, people began to call in, saying they couldn’t get out of bed. The pills were making them sluggish, the needles caused swelling and redness; some patients’ pain ballooned to nightmarish levels. “The side effects were simply amazing,” Kaptchuk explains; curiously, they were exactly what patients had been warned their treatment might produce. But even more astounding, most of the other patients reported real relief, and those who received acupuncture felt even better than those on the anti-pain pill. These were exceptional findings: no one had ever proven that acupuncture worked better than painkillers. But Kaptchuk’s study didn’t prove it, either. The pills his team had given patients were actually made of cornstarch; the “acupuncture” needles were retractable shams that never pierced the skin. The study wasn’t aimed at comparing two treatments. It was designed to compare two fakes.

Perhaps most interesting: placebos work even when patients know they are placebos.

But years of considering the question led him to his next clinical experiment: What if he simply told people they were taking placebos? The question ultimately inspired a pilot study, published by the peer-reviewed science and medicine journal PLOS ONE in 2010, that yielded his most famous findings to date. His team again compared two groups of IBS sufferers. One group received no treatment. The other patients were told they’d be taking fake, inert drugs (delivered in bottles labeled “placebo pills”) and told also that placebos often have healing effects.

The study’s results shocked the investigators themselves: even patients who knew they were taking placebos described real improvement, reporting twice as much symptom relief as the no-treatment group. That’s a difference so significant, says Kaptchuk, it’s comparable to the improvement seen in trials for the best real IBS drugs.

The article lists various caveats and skepticism but overall it seems like there’s something to the placebo treatment.