|
Menu |
|
This review of Placebo: The Belief
Effect
appeared in The Journal
of the Royal Society of Medicine
in April 2003.
J R Soc Med 2003; 96:199-200
Placebo: the Belief EffectMiddlesex University Business School, Hendon NW4 4BT, UK Placebo may have been the mainstay of medical practice untilthe 20th century, but how it works and what role it plays inthe current research culture is only now being investigated. In Placebo: the Belief Effect 1 —a very lively explorationof the role of placebo in the development of medicine and itsmore recent use as a key tool of medical research—Dylan Evans shows us how little is still known, and furthermore castsconsiderable doubt on those who have so far professed to understandit. He then goes on to review new findings on the molecularlinkage between brain and immune system that might lie behindthe effect. This occurs, he suggests, through suppression of theacute phase response as revealed in such signs as pain, inflammation, swellingand fever. The science is set out in some detail, but this isnot just a book for doctors and researchers; the use of engagingexamples makes much of it enjoyable reading for those not medicallyqualified. Evans begins by recounting the circumstances in which placebo emerged, with a penetrating critique of Beecher's seminal work published in JAMA in 1955. Although bad science, he says, makesbad practice, it can still yield important pointers for furtherresearch. Looking at progenitors of the clinical trial he tellsof an experiment conducted by Frederick II in Sicily in the 13th century. To see how exercise affected the digestion, the King gave two knights a meal, then sent one to bed and the other out hunting. What they were probably not told was that he would kill them to compare the contents of their alimentary canals. Some progress has been made since then, principally in the 20th century with the use of randomization and the placebo control. For the non-medical reader it is unfortunate that not untilnearly half way through the book are we offered an explanationof standard research practice—e.g. setting out the differencebetween blind and double blind. By this point Evans has treatedus to an array of research examples in support of his arguments.In chapter 2 we read of Shapiro's work indicating differential effects of pill colour on treatment outcomes—an observation thatshould have been of great interest to the pharmaceutical industry.His exploration of current research methods also points to designweaknesses, especially if we accept his theory that placebo suppresses immune responses; comparisons of placebo with ‘no treatment’ might be enlightening if ethically acceptable. Evans' analysis points to the influence of external environmentalfactors on body—brain interactions, and we see possible mechanisms for both the ‘doctor-effect’ describedby Balint 2 and the benefits reported by patients from alternative and complementary therapies. (These benefits are acknowledged by British general practitioners: by the year 2000 more than half were providing direct access to such services.) What is less clear in the book is what one might call the boundary of belief—the extentto which any intervention must be consciously perceived for it to be effective. As he says, ‘with most brain processes... the goal of conceptual integration is still a long way off in practice’. Damasio 3 would agree. While there is some discussionof this point, together with the ethical restrictions now placedon research, it may be that the most effective way to determinethese boundaries will be through working with groups who sofar have received little attention—old people, those with mental illness, or children. Until quite recently babies wereperceived to have low sensitivity to pain, and treated accordingly,because doctors laid importance on cognition rather than theevolutionarily older sensory systems. Evans believes that the historicalevolution of different aspects of the human body offers a wayto fill gaps in knowledge of the placebo response—notably, immune reactions of various evolutionary ages, and their consequences. A whole chapter is devoted to the power of belief and its effectson physiology, highlighting the possible differences betweenindividuals, however well matched they are in statistical terms.What the book does not discuss is the conflict between such personal characteristics and evidence-based medicine (EBM), which depends on observations in groups rather than individuals. 4 Evans' analysis suggests that there are ‘complex waysin which people come to believe their treatment will be effective,sometimes putting the evidence of their senses above the voiceof authority, while at other times doing completely the opposite’.Many within the medical profession continue to be guided by similar instincts, describing their thought processes as clinical judgment. It is issues of this sort that have made EBM so hard to implement. Asdiscussed in chapter 5, a dampening effect of placebo on theacute phase response could be interpreted as reflecting the uniquely human social expectation of care from others. 5 Perhapsthe most intriguing part of the book, coming from this former psychotherapist, is the exploration of the role of psychotherapy.His conclusion is that, even if psychotherapy proves to be nomore than placebo, this does not necessarily detract from itsusefulness; and, if it is better than placebo, our failure to understandhow it acts on the brain may be analogous to our ignorance of exactlywhy certain drugs are effective. Evans is at his best when writing frompersonal experience. Whatever the reader's conclusions aboutthe scientific arguments, his examples and delivery providea thoroughly engaging way into this debate. REFERENCES
This page was last updated: 1 April 2003 |