THE placebo effect has been known about since the beginnings of medicine. Indeed, it used to be just about the only medicine doctors could offer their patients – reassurance that a treatment will work, with the result that it often did. What nobody realised until recently is just how powerful and complex the effect is.
It turns out that a patient’s state of mind, awareness of their condition and expectations of the care they are about to receive can influence pretty much every facet of medicine, from consultations with a doctor to clinical trials of a new drug. For example, one set of researchers has found that the anxiety-relieving drug diazepam doesn’t work unless patients know they are taking it. Similarly, morphine is significantly more effective when people are told they are being given it. In both cases the placebo effect is critical to the drug’s effectiveness (see “One thing that don’t make sense”).
The potency of the placebo effect can be a boon for doctors, especially when faced with patients whose symptoms do not respond to any known treatment. found that nearly half the physicians in the US consciously use the placebo effect in their prescribing. Fewer than half of these tell the patient what they are doing, fearing that if they did the placebo wouldn’t work.
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Is this kind of deception acceptable? Many think it is, so long as it helps the patient. Still, deception may not always be necessary: a study earlier this year showed that a placebo can work even when the patient is aware they are taking it. Children with attention-deficit hyperactivity disorder can manage just as well on a lower dose of medication if they also take what they are explicitly told is a “booster” capsule, which “has no drug in it… but it may help you to help yourself”. Given that many drugs have nasty side effects, this kind of “open label” use has obvious potential.
But there is a flip side, as this all has implications for the way clinical trials are done. Given the many and complex ways in which people respond to placebos, the standard idea of discovering the effectiveness of a drug by testing it against a “sugar pill” now looks a little simplistic. Clinical trials may have to become more sophisticated: for example, by disguising when a drug treatment starts or ends, or telling some participants that they received the drug when they actually got the placebo.
Again, these methods involve a degree of deception, and the ethics of that will have to be thrashed out. What’s clear is that the usefulness of a drug, for example, depends on a lot more than the chemicals in a pill, and that a deeper understanding of the placebo effect could turn it into an invaluable tool for reducing suffering.
