Placebos can work even when patients know they're placebos.
In a 2010 Harvard trial, people with irritable bowel syndrome were openly given 'sugar pills' and told exactly that. They still reported markedly better symptom relief than a group given nothing. The ritual of treatment seems to heal a little, even without the deception.
The placebo effect is usually thought to depend on belief: a patient improves because they think they have received a real drug. That assumption creates an ethical problem, because using placebos in the clinic seems to require deceiving people.
In 2010, Ted Kaptchuk and colleagues at Harvard tested whether deception was actually necessary. They recruited 80 patients with irritable bowel syndrome. Half received no treatment. The other half were given pills in a bottle labelled 'placebo pills', told they contained no medicine, and told that placebos had been shown to produce improvement through mind–body self-healing processes.
After three weeks, the open-placebo group reported significantly better symptom relief and global improvement than the no-treatment group. Later 'open-label placebo' studies have reported similar effects for chronic back pain, cancer-related fatigue and allergies.
Why would it work? Researchers point to expectation, conditioning from past experiences of taking medicine, and the effect of attentive care itself. The effects tend to be strongest for symptoms people experience subjectively, such as pain, fatigue or nausea, rather than for the underlying course of a disease. A sugar pill will not shrink a tumour. But the studies suggest that the act of being treated, a warm relationship, a clear ritual, is not just packaging. It is part of the medicine.
Source: Kaptchuk et al. (2010), PLOS ONE · Open access (CC BY)
