Saturday, February 20, 2010

Homeopathy and the placebo effect

I've been thinking about homeopathy. This was prompted by a piece by Michael Brooks in the Aug 20, 2008 issue of New Scientist attesting to the efficacy of the placebo effect.

Then just recently I came across a second article by the same author in the Guardian Science Blog that discusses the placebo effect in the context of homeopathy.

For a simple sugar tablet to make you better, it helps if you believe it to be a real, potent medicine. Furthermore, it seems the effectiveness of any remedy is increased if patients are given time, listened to at length and fully consulted about their symptoms, feelings and treatments.

In a typical homeopathic consultation the practitioner will start by taking a detailed personal history covering physical, mental and emotional states. After identifying a remedy appropriate both to the patient and to his or her specific condition the remedy is potentised somewhat ritualistically by means of a series of dilutions and shakings (succussions).

All of which suggests to me that if the placebo effect is real and effective then homeopathy is perfectly configured to exploit it.

So instead of getting worked up about the fact that homeopathic remedies are so dilute as to contain no trace of their active agent, we should be giving serious thought to experiments designed to provide insights into the therapeutic process.

Here's the sort of experiment I'd like to see done:

Firstly, you recruit a statistically significant number of subjects all suffering from a condition considered (by homeopathic practitioners) to be treatable.

Half the subjects are told they will not participate further in the trial and that they will constitute a control group (group A). The other half are given individual treatment by a group of homeopathic practitioners, starting with a detailed case history and culminating in the identification and preparation of a remedy. The practitioners are told that the remedies will be delivered to all subjects once they have been correctly recorded and labelled and they have no further contact with their patients (at least until the study is concluded).

Of the subjects for whom remedies have been prepared, half are told (by the researchers) that the remedy will not be supplied to them (call this group B). The remaining subjects are all supplied with a course of pills but in half the cases (call it group C) the remedy prepared is replaced by a simple sugar pill. The only people to take the remedy identified and prescribed by the homeopath are those in group D (just 1 in 8 of the full set of participants).

At a series of regular intervals, all subjects are examined with respect to changes in their condition. It helps of course if the condition is such that it manifests itself in a measurable way (at least partially)

It is worth noting that groups C and D (considered in isolation) are engaged in a typical double-blind trial. And since such trials have so far failed to demonstrate the efficacy of homeopathy we might expect the same to be the case here. Or to put it another way: of the people who believe themselves to have undergone a full course of homeopathic treatment there might well be no evidence to suggest that the homeopathic remedy is any more or less effective than a simple placebo.

A similar uniformity of outcome might be anticipated amongst the people in groups A and B. None of these people were supplied with any pills and all believe themselves to be part of a control group.

The really interesting question is whether there would be any observable difference between the people who didn't receive a remedy (groups A and B) and those who did (groups C and D). If the second group were to demonstrate a significantly better outcome than the first then we would be onto something. Nevertheless, while homeopathy might take credit for the method of delivery, it would be the placebo effect that could justifiably lay claim to the attribution.

So while I am personally somewhat sceptical about homeopathy, I find myself having to allow for the possibility that, for many people at least, recovery from certain forms of physical and mental illness can entail a degree of willing self-deception.

I don't believe in offering homeopathic treatment on the NHS. Instead I believe we should be working towards a state of affairs where all doctors are trained to recognise the degree to which listening, attentiveness and respect can have a measurable effect on clinical outcomes. Who knows; homeopaths might have something to teach them in this area.


  1. You might be interested in "Bad Science" by Ben Goldacre - he also does a column of the same name in the Guardian - it discusses this subject in some detail and it's very interesting (and discusses some of the studies into the very things you are musing)

  2. Anonymous3:38 pm

    Glad to see you working on the problem. A diagram would make your ideas much clearer. :>)

  3. I received a comment on this piece which, despite being approved, was not published - so I am attempting to recall it here. It asked how one can account for the efficacy of homeopathy when administered to zoo or farm animals.

  4. Anonymous7:28 pm

    Now look what you've started...

    Everyone's designing experiments :>)

  5. Thanks for the Richard Dawkins reference. His experiment is remarkably similar to mine ...

    He must be pinching my ideas.

  6. After recognizing a remedy suitable both to the patient and to his or her exact condition the remedy is potentised somewhat ritualistically by means of a series of dilutions and shakings.