This is a very interesting, but quite long, article about a mysterious phenomenon which is causing havoc in drug trials. The placebo (dummy) pills given to people seem to having a more powerful positive response than the drugs being tested.
an extract from the article
In a study last year, Harvard Medical School researcher Ted Kaptchuk devised a clever strategy for testing his volunteers' response to varying levels of therapeutic ritual. The study focused on irritable bowel syndrome, a painful disorder that costs more than $40 billion a year worldwide to treat. First the volunteers were placed randomly in one of three groups. One group was simply put on a waiting list; researchers know that some patients get better just because they sign up for a trial. Another group received placebo treatment from a clinician who declined to engage in small talk. Volunteers in the third group got the same sham treatment from a clinician who asked them questions about symptoms, outlined the causes of IBS, and displayed optimism about their condition.
Not surprisingly, the health of those in the third group improved most. In fact, just by participating in the trial, volunteers in this high-interaction group got as much relief as did people taking the two leading prescription drugs for IBS. And the benefits of their bogus treatment persisted for weeks afterward, contrary to the belief, widespread in the pharmaceutical industry, that the placebo response is short-lived.