Placebos: more than fake drugs

I’ve been watching the BBC2 programme Horizon for over 50 years; it’s now in its 57th season and I have to say it continues to fascinate me in the same way as it did when a far-sighted David Attenborough introduced it all those years ago.

Recently, redoubtable medical journalist Dr Michael Mosley ran a trial on 100 people with chronic back pain. He pretended that half the group would get an active drug, the other half an inactive placebo. In fact everyone received the placebo, yet after 3 weeks, 45% of the group reported a significant improvement in their symptoms.

As a doctor I have seen the placebo response work on countless occasions. Obviously doctors cannot hoodwink their patients by giving them one while pretending it is active, though, amazingly, a number of patients improve even when they know they are getting the placebo. In fact some would argue that drugs which the doctors believe are active, such as Prozac, or old-school antibiotics, are actually working via this effect. And remembering that those drugs often have unpleasant side effects, it makes one wonder whether it might not be a better idea to give them a placebo to start with.

The most dramatic example of a placebo in action I have ever seen was at medical school, when a patient was injected with a dilute dextrose solution. Or that’s what she thought. In fact she was given plain, distilled water. But the reaction was astounding. Within a minute of the injection, the patient’s face became swollen and purple, she began to shake uncontrollably and within two minutes had collapsed unconscious. She experienced a phenomenon called “angio-oedema” a catastrophic reaction sometimes associated with severe allergy. But you can’t be allergic to water: our bodies are 90% water after all. So what happened? To be honest, nobody knew then and nobody knows now.

The placebo response is still poorly understood. In the test group above, why did 45% of the group experience an improvement, while 55% did not? The response is independent of age, IQ or social
background. As a doctor I’ve long recognised that if you give a patient something along with a forceful promise that it’s going to do the trick, it is far more likely to work than otherwise. If I was still working now, would I offer people placebos with the words: “Look, I know there’s nothing in this pill, but research has shown that even so, it often works”? You know, I think I might. And let’s face it, it’s no more or less than homoeopathists do every day of the week...