Wednesday, 27 March 2013

Book review: Meaning, Medicine and the Placebo Effect

Title: Meaning, Medicine and the Placebo Effect (2002)
Author: Daniel Moerman
Publisher: Cambridge University Press

In this book, an anthropologist offers an outsider’s view of medicine. The book is not restricted to an examination of the placebo effect (in fact, the author suggests abandoning the term, instead using “meaning response”); it asks readers to see all of medicine (and indeed biology) in its social and cultural context. The author shows that much of what we “know” isn’t necessarily true (or more confusingly, that it might be true in certain contexts). In that vein, he criticises doctors for dressing in science (empirical evidence), but practicing experiential evidence, and therefore not being able to see that what they “know” (based on tradition and their own experience) might not be true (despite being able to construct biological mechanisms to explain the perceived effect).

I like reading books about medicine by non-doctors (see book review: Limits to Medicine); they offer such a refreshing and challenging view of medicine, and this book is no exception.

Professor Moerman (professor of anthropology based in the USA) offers an explanation for the placebo effect, starting with the (correct) observation that placebos, by definition, have no effect. Apart from regression to the mean and natural history, the placebo effect is best represented by the term “meaning response”, i.e. the response depends on the meaning perceived by factors such as the form of the treatment (red pills versus blue pills), the method of delivery (the doctor’s behaviour and language) and the knowledge surrounding this. And the meaning of all these factors differs between cultures.

Importantly, the author points out that the meaning response is largely driven by the doctor delivering the treatment, not the patient receiving the treatment. He argues that this response is strong and is often not considered when assessing the effects of medical therapy.

And it is getting harder to measure the true effectiveness of medicine as the use of placebo controls in research becomes harder to justify on ethical grounds (although I would argue, and have argued, the opposite).

The author offers many examples of research that has been conducted around placebos and the non-specific effects of medicine; most of these make interesting reading on their own, without the context he provides. However, he falls short of providing a complete, unifying theory of the placebo effect, and the overall feeling at the end of the book is that the meaning we interpret from the act of medicine (form, context, language etc.) can affect biology, but how much it does so is (perhaps deliberately) left open to interpretation.

He also lets medicine off the hook occasionally. For example, he shows how placebos have led to dramatic improvements in cardiac patients (e.g. angina) over history, calling into question many past treatments, but then, after pointing out the lack of placebo testing of current treatments such as bypass surgery, says that we know it works because we do it much better now. The application of anthropological and cultural methods (not always amenable to experimental methods) to medicine is his theme, but I think he should judge scientific claims using scientific methods. By assuming that treatments work, he is falling for the same trap that he accuses the doctors of: accepting ‘common knowledge’ as truth.

The bottom line
I believe, as does the author, that doctors need a better understanding of how much medicine depends on non-specific therapeutic effects (regression to the mean, natural history and the meaning response) for its perceived effectiveness, and consequently, how we might be wrong about many current treatments that we “know” to be effective.

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