From abductus and abortus to zona pellucida, none of medicine’s lengthy dictionary of Latinate terms is so commonly used, yet so undervalued, as the first person singular future indicative of placere, to please. “Placebo”-anglicised as a noun-means a dummy pill: something physiologically inert, the effects of which are a consequence of the taker’s own expectations of benefit. By what subtle interplay of nerves and hormones the state of our minds can influence the condition of our bodies is still obscure. But the greater puzzle about the placebo effect is that while all doctors take it seriously when doing clinical research, many disregard it when treating patients who are not enrolled in a research project.
Few people outside medicine appreciate the nature or power of placebos. Dictionary definitions are not helpful. The New Shorter OED has it as: “A pill, medicine, procedure etc prescribed more for the psychological benefit to the patient of being given a prescription than for any physiological effect.” In other words, a mere comforter: something to stop you worrying about problems rather than solving them.
But to suggest that they do not benefit the patient is to miss the point. Indeed, the full measure of the placebo effect is quite startling. Studies comparing active treatments with dummy pills or sham procedures consistently show that one third of patients respond in some measure to a placebo. The significance of this remarkable fact-and the potential for confusion-can be appreciated by thinking of a chronic disease for which a practitioner claims to have devised the first remedy. Suppose this person recruits a group of sufferers and treats just half of them; suppose that six weeks later, 30 per cent of the treated group-but none of the untreated group-have improved. Optimists ignorant of the placebo effect will be tempted to hail the remedy as a breakthrough. In truth, these findings prove nothing.
The right way to do the experiment is, of course, to have three groups: one treated with the remedy; one left untreated; and one given a dummy pill. If the first and third groups improve equally, the benefits of the new remedy are nothing more than the self-healing effects of the patient’s desire to have something which works.
Medical researchers have known all this for years. Recognising the power of the placebo, they use elaborate procedures for discounting it. Only improvements greater than the placebo response are accepted…