And for my next trickBMJ 2008; 337 doi: http://dx.doi.org/10.1136/bmj.a2492 (Published 10 November 2008) Cite this as: BMJ 2008;337:a2492
- Wendy Moore, journalist, London
In the laudable history of clinical trials, little has given doctors more pleasure than the demonstration of the placebo effect, particularly when it is used to undermine unorthodox treatments.
John Hunter, the tireless 18th century experimenter, could scarcely conceal his delight when conducting a trial on the popular folklore remedy of spider’s web. After secretly dosing a patient who had the “ague” with the treatment, he found that it had “not the slightest effect”; yet once his patient had been informed of the intervention, “the effect was produced,” he gloated.
As a maverick who regarded conventional and alternative treatments with almost equal disdain, Hunter was one of the few—and possibly the first—to test a standard medicine against a placebo. Convinced that mercury, the stock treatment for gonorrhoea, was largely ineffectual, Hunter gave several unsuspecting patients pills made of bread. “The patients always got well,” he reported, although he hedged his bets by adding, “but some of them, I believe, not so soon as they would have done, had the artificial methods of cure been employed.”
Better known and certainly more systematic were the placebo tests performed on “mesmerism,” a form of hypnotism championed by the showman Franz Anton Mesmer, at the behest of Louis XVI in 1784. Rising to the challenge with gusto, French scientists blindfolded a series of patients who were subjected to authentic and fake mesmerism in—literally—the first blind placebo trials.
To their obvious joy (there was no double blinding) the researchers found no appreciable difference in outcome, even proving that mesmerism had no effect when it was applied surreptitiously, and gleefully dismissed the treatment’s perceived effects as “determined by the imagination.”
Certain that this placebo effect explained the popularity of alternative therapies in general —although not of course their own useless remedies—doctors next turned controlled trials on metal “tractors,” or rods, which a Connecticut practitioner, Elisha Perkins, claimed could relieve pain by conducting “electrode” fluid away from the body.
Ingeniously constructing a sham pair of tractors from painted wood, the English physician John Haygarth tested the instrument on five patients with rheumatism in 1799. Four of the five reported a remarkable improvement, including one who could walk much more easily, prompting Haygarth to proclaim: “Such is the force of Imagination!” Shrewdly, Haygarth recommended that orthodox doctors harness the placebo effect by endeavouring to instil confidence whenever they recommended a treatment, and he noted wryly: “This explains what has been frequently observed, that the same remedy will produce more beneficial effects when prescribed by a famous physician, than by a person of inferior character.”
Gathering pace, doctors next fixed homoeopathy in their sights. In a large trial in St Petersburg beginning in 1829, physicians divided army patients into three groups to receive conventional treatment, homoeopathic remedies, and placebo bread pills. Unsurprisingly the patients who received the placebos did the best. Equally unsurprisingly, although the tests exposed homoeopathy, they did little to diminish confidence in the routine bloodletting and toxic concoctions touted by orthodox physicians.
Finally, in a landmark article in 1955, the medical campaigner Henry Beecher described the power of the placebo effect in conventional and unconventional medicine alike. But as far back as 1689 the London physician Gideon Harvey had already given a passable description. Berating his orthodox colleagues, Harvey proclaimed, “It is to the Art of Expectation Physicians are indebted for their Reputation, that occasions an ignorant world to continue the use of them.”
Cite this as: BMJ 2008;337:a2492
Sources: W Moore, The Knife Man (London, Bantam Press, 2005); T Kaptchuk, “Intentional ignorance: a history of blind assessment and placebo controls in medicine,” Bulletin of the History of Medicine, 1998;72:389-433; M Dean, “‘An innocent deception’: placebo controls in the St Petersburg homeopathy trial, 1820-30,” Journal of the Royal Society of Medicine, 2006;99:375-6; G Harvey, The Art of Curing Diseases by Imagination (London, 1689).
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