Reading passage Go to the questions
The power of believing
A A placebo is a treatment with no active ingredient, such as a sugar pill or a salt-water injection, that is given in place of a real medicine. For decades, placebos have been used in clinical trials as a point of comparison: if a new drug performs no better than a placebo, it is unlikely to be effective. But placebos have also attracted interest in their own right, because patients who take them sometimes feel genuinely better.
B The idea that placebos are remarkably powerful owes much to a 1955 paper by the American anaesthetist Henry Beecher, entitled "The Powerful Placebo". Reviewing a series of studies, Beecher concluded that roughly a third of patients experienced relief from a placebo alone. His figure was widely quoted for the rest of the century, and the "placebo effect" entered popular culture as evidence that the mind could heal the body.
C Later researchers were more cautious. Many conditions improve naturally over time, and patients often enter studies when their symptoms are at their worst, so some improvement would be expected even with no treatment at all. Beecher's analysis did not separate these factors from the effect of the placebo itself. In 2001, the Danish researchers Asbjørn Hróbjartsson and Peter Gøtzsche reviewed trials that had compared a placebo group with a group that received no treatment. They found little evidence that placebos had powerful effects in general, although there were signs of a modest benefit for pain and for outcomes that patients reported themselves.
D This did not mean that expectations were irrelevant. Brain-imaging studies have shown that when people expect pain relief, activity changes in regions of the brain involved in processing pain. Expectations can also work in the opposite direction. Patients warned about possible side effects of a drug sometimes report those side effects even when they have been given a placebo, a phenomenon known as the "nocebo" effect.
E One of the most surprising recent findings concerns "open-label" placebos. In 2010, a team led by Ted Kaptchuk at Harvard gave patients with irritable bowel syndrome pills that they were told openly contained no medicine. Compared with a group that received no pills, these patients reported a significantly greater improvement in their symptoms. Similar studies have since been carried out for other conditions, with mixed results.
F The open-label research matters because it may offer a way around an ethical problem. Giving a patient a placebo while pretending it is a real drug involves deception, which most medical codes do not allow. If honesty does not remove the benefit, doctors might one day be able to use the patient's own expectations openly, alongside, rather than instead of, effective treatment.
