The body has remarkable powers of recovery, which the mind can trigger to produce a wide range of healing effects. One way of activating this healing potential is to give a patient a ‘dummy’ treatment that he or she expects to have a curative effect. Such treatment is known as a placebo.
Fifty years ago, one of the most commonly prescribed treatments in general medicine was a sticky, bright pink, strong-smelling mixture called a ‘special tonic.’ Family doctors handed out this mysterious substance with grave instructions about exactly how and when it should be taken and encouraged patients to believe that it had powerful healing properties. In fact, the tonic was little more than colored syrup with no direct curative power. Yet the doctors were still being truthful when they implied that it could heal. Patients who believed in the special tonic usually showed improvement and reported feeling better. T his placebo effect has been observed since medicine began. [Indeed, until the early 20th century, most pills and potions worked in this indirect way. The word ‘ placebo ‘ is derived from the Latin ‘ I shall please’ – an acknowledgment, probably, that doctors often employed placebos to ‘please ‘ their patients.
The power of belief
Any form of treatment can be a placebo, and those with the most powerful effects are generally the ones believed by the patient to be the most effective type of treatment. For example, patients who believe in ‘natural medicine’ are more likely to find that herbs can cure their complaints. At the same time, people who prefer to trust modern pharmacology may do better with synthetic medicine. Similarly, placebos given by injection are likely to have a greater effect than pills because they are more invasive, and so are generally perceived to be more powerful. Probably the most dramatic placebo of all is surgery. In the 1950s, when surgeons were cavalier about patient rights, a group of people with heart disease were subjected without their knowledge to an experiment intended to test the efficacy of a particular operation. Half the patients had the operation, which involved opening the chest and tying off an artery, while the other half was just cut open and sewn up again. Afterward, the patients who had undergone the actual operation were found to be in no better or worse health than those who had merely been opened up. The experiment was repeated by different surgeons, and this time, the patients who had just been cut open showed even greater improvement than those who had the operation. The improvements were considerable: one patient who had not been operated on was able to run on a treadmill for ten minutes after the treatment, whereas he could barely manage four minutes before. His underlying condition was unchanged, but his ability to function improved enormously. As functional competence is generally the measure of health, it would be true to say that his health had improved.
Placebo-controlled clinical trials
The surgery experiment was an example of a placebo-controlled clinical trial – that is, a study in which the effect of medical treatment is compared to the effect of placebo treatment on a ‘ control’ group. In this case, previous studies had compared patients who had undergone surgery with others who had received no treatment at all, which suggested that the operation was useful. However, the placebo-controlled trial showed that the improvement seen after the operation was due to the patient’s belief that they had received effective treatment. The surgical procedure was shown to give no additional benefit, and so was abandoned.
Surgery is rarely tested against a placebo, but all new drugs must show that they compare favorably to a placebo before they are licensed. Some trials include a third group of patients who receive no treatment at all, and these trials have produced a vast amount of evidence to show just how powerful the placebo effect can be. One large trial involving nearly 4,000 heart- disease patients over five years found no difference at all in the number of deaths among those who took a real drug and those who took a placebo. However, there was an enormous difference- about 80 percent – between the health of those who took their pills regularly, whether placebo or real and those who did not. This strongly suggests that belief in the pills, as demonstrated by keeping to the regime, was more important than any direct effect of the trial drugs. (Effective drugs show a distinct benefit over a placebo, and a drug that performed no better than a placebo would not receive a license.)
The importance of recognition
The placebo effect does not always depend on patients believing they have received effective treatment – simply having symptoms recognized and taken seriously makes an enormous difference. A study of 600 patients who visited their family doctor for sore throats found that those who felt they had been treated sympathetically recovered more quickly. A dose of sympathy had generally been more effective, it seems, than a course of antibiotics.
Some complementary therapies depend on the placebo effect for their efficacy, but it is difficult to test this because a placebo element is usually built into complementary treatments. A consultation with a complementary therapist will often involve taking a detailed patient history and listening carefully to the patient. It may also involve ‘ hands-on ‘ treatment, like aromatherapy, massage, or body manipulation. These elements are most certain to have a placebo effect, but if you remove them, there may be little of the therapy left to assess. This is why it can be difficult (although not impossible ) to test complementary treatments using rigorous scientific measures.
The brain-body response
The activation of different physiological mechanisms in the body brings about the placebo effect. Pain can be relieved by the release of natural endorphins – morphine-like substances in the brain. The relief of a problem such as constipation or irritable bowel syndrome may be due to nervous system mechanisms that relax the smooth muscle of the intestine. Infections, and possibly even m mo u rs, may be reduced by the brain activating immune system responses.
However, although physiologically based, the placebo effect is subject to learning and modification. If, for example, you have learned to associate pain relief with taking a small white pill, that association alone can bring about pain relief whenever you take a similar white pill – regardless of what it contains. As long as you believe it is a painkiller, it can have a curative effect. In one experiment, people were given a tablet that produced heart palpitations. When they were later given an inert but identical-looking lozenge, their heart rates increased to the same extent as with the active substance. The placebo effect is thus not always benign but tends to produce the effects that the patient expects the treatment to have, which may include unpleasant side effects. Indeed, the high level of side effects reported by many people taking a placebo has prompted some researchers to question the general assumption that placebos are harmless. Placebos, then, rely heavily on the patient’s expectations of the treatment’s effectiveness. The body simply ‘does what is expected of it’ – whatever that is in each case.
