2002GreatExpectations

1 GREAT EXPECTATIONS: THE EVOLUTIONARY PSYCHOLOGY OF FAITH- HEALING AND THE PLACEBO EFFECT1 I said that the cure itself is a certain leaf, but in addition to the drug there is a certain charm, which if someone chants when he makes use of it, the medicine altogether restores him to health, but without the charm there is no profit from the leaf. Plato (Charmides, 155-6). I too have a story about leaves and charms. My little daughter, Ada, did not encounter stinging nettles until we returned to England from America when she was nearly four years old. We were in the fields near Cambridge. I pointed out a nettle to her, and warned her not to touch. But, to reassure her, I told her about dock leaves: “If you get stung,” I said, “then we’ll rub the bad place with a dock leaf and it will very soon be better.” Ten minutes later Ada had taken her shoes and socks off and had walked into a nettle patch. “Daddy, daddy, it hurts. Dad do something..” “It’s all right, we’ll find a dock leaf.” I made a show of looking for a dock leaf. But then – in the interests of science – I played a trick. “Oh dear, I can’t see a dock leaf anywhere. But here’s a dandelion leaf,” I said, picking a dock leaf. “I wonder if that will work. I’m afraid it probably won’t. Dandelion’s aren’t the same as dock leaves. They just aren’t so magic.” Ada’s foot had come up with a nasty rash. I rubbed it with the dock leaf which Ada thought to be a dandelion. “Ow, Daddy, it’s no better, it still hurts. It’s getting worse.” And the rash certainly looked as bad as ever. “Let’s see if we can’t find a proper dock leaf.” And we looked some more. “Ah, here’s just what we need,” I said, picking a dandelion leaf. “This should work.” I rubbed Ada’s foot again with the dandelion leaf which she now believed to be a dock. “How’s it feel now?” “Well, a little bit better.” “But look the rash is going away” – as indeed it was. “It does feel better”. And within a couple of minutes there was nothing left to show. Nick Nicholas Humphrey, "The Mind Made Flesh", Chapter 19, pp. 255-288, Oxford University Press, 2002 2 So, dock leaf magic clearly works. And yet dock leaf magic is placebo magic. Dock leaves, as such, have no pharmacologically relevant properties (any more than do dandelion leaves). Their power to heal depends on nothing other than the reputation they have acquired over the centuries – a reputation based, so far as I can gather, simply on the grounds than that their old English name, docce, sounds like the Latin doctor, hence doctor leaf, and also that they happen providentially to grow alongside nettles. But father magic clearly works too. Ada, after all, simply took my word for it that what was needed was a dock leaf. And very likely if I had merely blown her foot a kiss or said a spell it would have worked just as well. Maybe father magic is also a placebo. We should have a definition. Despite this talk of magic, there’s every reason to believe that, when a patient gets better under the influence of a placebo, normal physiological processes of bodily healing are involved. But what’s remarkable and what distinguishes placebos from conventional medical treatments is that with placebos the process of healing must be entirely self-generated. In fact with placebos no external help is being provided to the patient’s body except by way of ideas being planted in her mind. Let’s say, then, that a placebo is a treatment which, while not being effective through its direct action on the body, works when and because: C the patient is aware that the treatment is being given C the patient has a certain belief in the treatment, based, for example, on prior experience or on the treatment’s reputation C the patient’s belief leads her to expect that, following this treatment, she is likely to get better C the expectation influences her capacity for self-cure, so as to hasten the very result that she expects. How common are placebo effects, so defined? The surprising truth seems to be that they are everywhere. Stories of the kind I’ve just recounted about Ada are not, of course, to be relied on to make a scientific case. But the scientific evidence has been accumulating, both from experimental studies within mainstream medicine and from the burgeoning research on 3 alternative medicine and faith healing. And it shows beyond doubt that these effects are genuine, powerful and remarkably widespread.2 Andrew Weil, one of the best known advocates of alternative medicine, now argues that “the art of medicine” in general “is in the selection of treatments and their presentation to patients in ways that increase their effectiveness through the activation of placebo responses.” 3 And he describes in his book, Spontaneous Healing, the range of things that he has found from his own experience can do the trick. “Over the years . . . patients have sung the praises of an astonishing variety of therapies: herbs (familiar and unfamiliar), particular foods and dietary regimens, vitamins and supplements, drugs (prescription, over-the-counter, and illegal), acupuncture, yoga, biofeedback, homeopathy, chiropractic, prayer, massage, psychotherapy, love, marriage, divorce, exercise, sunlight, fasting, and on and on. . . In its totality and range and abundance this material makes one powerful point: People can get better.”4 What’s more, as Weil goes on, “people can get better from all sorts of conditions of disease, even very severe ones of long duration.” Indeed experimental studies have shown that placebos, as well as being particularly effective for the relief of pain and inflammation, can for example speed wound healing, boost immune responses to infection, cure angina, prevent asthma, lift depression, and even help fight cancer. Robert Buckman, a clinical oncologist and professor of medicine, concludes that “Placebos are extraordinary drugs. They seem to have some effect on almost every symptom known to mankind, and work in at least a third of patients and sometimes in up to 60%. They have no serious side-effects and cannot be given in overdose. In short they hold the prize for the most adaptable, protean, effective, safe and cheap drugs in the world’s pharmacopoeia.” Likewise, another medical authority, quoted in a5 recent review in the British Medical Journal, dubs placebos “the most effective medication known to science, subjected to more clinical trials than any other medicament yet nearly always doing better than anticipated. The range of susceptible conditions appears to be limitless.”6 “Limitless” may be an exaggeration. Nonetheless, it’s fair to say that just about wherever placebos might work, they do. In other words, wherever a capacity for self-cure exists as a latent possibility in principle, placebos will be found to activate this capacity in practice. It’s true that the effects may not always be consistent or entirely successful. But they certainly occur with sufficient regularity and on a sufficient scale to ensure that they can and do make a highly significant contribution to human health. And there’s the puzzle: the puzzle that I’ll try to address in this paper from the perspective of evolutionary biology. If placebos can make such a contribution to human health, then what are 4 we waiting for? Why should it be that we so often need what amounts to outside permission before taking charge of healing our own bodies? I can illustrate the paradox with one of Weil’s case histories. He describes the case of a woman with a metastatic cancer in her abdomen who refused chemotherapy and relied instead on dieting, exercise and a regime of “positive thinking” including “regular meditation incorporating visualization of tumour shrinkage” – following which, to the physicians’ astonishment, the tumour completely disappeared. Weil asks: “What happened in this woman’s abdomen that eliminated widely disseminated cancer and restored her internal organs to good health? Her healing system, probably making use of immune mechanisms, was surely responsible; but why did it not act before?”7 Precisely. Why? Why should her bodily immune system be prepared, apparently, to let her die unless and until her mind decided otherwise? Weil asks the question as a doctor, and his “why?” is the why of physiological mechanism: “what happened?”. But I myself, as I said, want to take the perspective of an evolutionist, and my “why?” is the why of biological function: “why are we designed this way?”. There are two reasons for thinking that evolutionary theory may in fact have something important to say here. One reason is that the human capacity to respond to placebos must in the past have had a major impact on people’s chances of survival and reproduction (as indeed it does today), which means that it must have been subject to strong pressure from natural selection. The other reason is that this capacity apparently involves dedicated pathways linking the brain and the healing systems, which certainly look is if they have been designed to play this very role.8 I’d say therefore it is altogether likely that we are dealing with a trait that in one way or another has been shaped up as a Darwinian adaptation – an evolved solution to a problem that faced our ancestors. In which case, the questions are: what was the problem? and what is the solution? I am not the first to ask these questions. Others have suggested that the key to understanding the placebo response lies in understanding its evolutionary history. George Zajicek wrote in The Cancer Journal a few years ago: “Like any other response in the organism, the placebo effect was selected in Darwinian fashion, and today’s organisms are equipped with the best placebo effects.” And Arthur and Elaine Shapiro wrote in a book, The Placebo Effect: “Does9 the ubiquity of the placebo effect throughout history suggest the possibility . . that positive 5 placebo effects are an inherited adaptive characteristic, conferring evolutionary advantages, and that this allowed more people with the placebo trait to survive than those without it?”10 But, as these quotations illustrate only too well, the thinking in this area has tended to be question-begging and unrevealing. I hope we can do better. So, let me tell you the conclusion I myself have come to. And then I shall explain how I have come to it, and where it leads. My view is this. The human capacity for responding to placebos is in fact not necessarily adaptive in its own right (indeed it can sometimes even be maladaptive). Instead, this capacity is an emergent property of something else that is genuinely adaptive: namely, a specially designed procedure for “economic resource management” that is, I believe, one of the key features of the “natural health-care service” which has evolved in ourselves and other animals to help us deal throughout our lives with repeated bouts of sickness, injury, and other threats to our well-being. Now, if you wonder about this choice of managerial terminology for talking about biological healing systems, I should say that it is quite deliberate (and so is the pun on NHS.) With the phrase “natural health-care service” I do intend to evoke, at a biological level, all the economic connotations that are so much a part of modern health-care in society. “Managed health-care” as it’s practised these days is of course not just to do with health – sometimes it isn’t even primarily to do with health – it is to do with balancing budgets, cutting costs, deciding resource allocation, operating a triage system and so on. I am suggesting that the same applies in crucial ways to nature’s own bodily healing systems. And the point is that, if that’s right, we can take a new theoretical approach. Suppose we adopt the point of view not of the doctors or the nurses in a hospital, but of the hospital administrator whose concern as much as anything is to husband resources, spend less on drugs, free up beds, discharge patients earlier and so on. Then, if we take this view of the natural health-care service, instead of asking about the adaptiveness of bodily healing as such, we can turn the question round and ask about the adaptiveness of features that limit healing or delay it. What we’ll be doing is a kind of figure-ground reversal, looking at the gaps between the healing. So let’s try it. And, in taking this approach, let’s go about it logically. That’s to say, let’s start with the bare facts and then try to deduce what else has to be going on behind the scenes to explain these facts, on the assumption that we are indeed dealing with a health-care system that has been designed to increase people’s overall chances of survival. Then, once we know 6 what has to be the case, we shall surely be well placed to take a closer look at what actually is the case! I am setting this out somewhat formally, and each proposition should be taken slowly. Here are some basic facts to start with: 1. 0ther things being equal, well-being is to be preferred to sickness. I assume this is uncontroversial. 2. People’s bodies and minds have a considerable capacity for curing themselves. This is what all the evidence of spontaneous recovery shows. 3. Sometimes this capacity for self-cure is not expressed spontaneously, but can be triggered by the influence of a third party. This is the basic placebo phenomenon. Then, it follows from 1 and 2, presumably, that: 4. In such cases, self-cure is being inhibited until the third-party influence releases it. And from the assumption that this pattern is non-accidental that: 5. When self-cure is inhibited there must be good reason for this under the existing circumstances; and when inhibition is lifted there must be good reason for this under the new circumstances. Put this together with the starting assumption that people want to be as well as they can be, and we have: 6. The good reason for inhibiting self-cure must be that the subject is likely to be better off, for the time being, not being cured. In which case: 7 7. Either there must be benefits to remaining sick, or there must be costs to the process of self-cure. Likewise: 8. The good reason for lifting the inhibition must be that the subject is now likely to be better off if self-cure goes ahead. In which case: 9. Either the benefits of remaining sick must now be less, or the costs of the process of self-cure must now be less. I’d say all the above does follow deductively. Given the premises, something like these conclusions must be true. In which case, our next step ought to be to turn to the real world and to find out how and in what sense these rather surprising conclusions could be true. The following are the most obvious matters which want unwrapping and substantiating: Is it indeed sometimes the case that there are benefits to remaining sick and, correspondingly, costs to premature cure?? Is it, as we might guess, more usually the case that there are benefits to getting better and, correspondingly, costs to delayed cure?? In either case, are there really costs associated with the process of cure as such?? Is it possible to predict how these costs and benefits will change according to external circumstances, so that the subject might in fact be able to take control of her own health budget?? Let me take these questions in turn. • Benefits of remaining sick / Costs of premature cure It depends how we define sickness. If sickness means a pathological condition of the body or mind that is unconditionally harmful, then there cannot of course ever be benefits to 8 remaining sick. However if sickness is taken more broadly to mean any abnormal condition of body or mind that you, the patient, find distressing and from which you seek relief, then it may be quite another matter. It has been one of the major contributions of evolutionary theory to medicine to remind us that many of those conditions from which people seek relief are not in fact defects in themselves but rather self-generated defences against another more real defect or threat. 11 Pain is the most obvious example. Pain is not itself a case of bodily damage or malfunction – it is an adaptive response to it. The main function of your feeling pain is to deter you from incurring further injury, and to encourage you to hole up and rest. Unpleasant as it may be, pain is nonetheless generally a good thing – not so much a problem as a part of the solution. It’s a similar story with many other nasty symptoms. For example, fever associated with infection is a way of helping you to fight off the invading bacteria or viruses. Vomiting serves to rid your body of toxins. And the same for certain psychological symptoms too. Phobias serve to limit your exposure to potential dangers. Depression can help bring about a change in your life style. Crying and tears signal your need for love or care. And so on. Now, just to the extent that these evolved defences are indeed defences against something worse, it stands to reason that there will be benefits to keeping them in place and costs to premature cure. If you don’t feel pain you’re much more likely to exacerbate an injury; if you have your bout of influenza controlled by aspirin you may take considerably longer to recover; if you take Prozac to avoid facing social reality you may end up repeating the same mistakes, and so on. The moral is: sometimes it really is good to keep on feeling bad. 12 So, in that case, how about the other side? • Benefits of getting better / Costs of delayed cure There is of course another side. Even when an ailment is one of these evolved defences, this does not necessarily mean there is nothing legitimately to complain of. For the fact is that, while the defences are there to do you good, they may still in themselves be quite a burden – not just because you do not like them, but because they can actually threaten your fitness directly, sometimes severely so. Take the case of pain again. Yes, it helps protect you. Nevertheless, it is by no means without cost. When pain makes it hard to move your limbs you may become more vulnerable to other dangers, such as predators. When the horribleness of pain takes all your attention you may no longer be capable of thinking clearly. When pain causes psychological stress it may make you bad-tempered or incapable or hopeless. It may even take away your will to live. In 9 cancer wards it’s said that patients in greatest pain are likely to die soonest and that treating the pain with morphine can actually prolong life. Or take some of the other defences I listed above. Fever helps fight infection, but it also drains your energy and can have damaging side effects such as febrile convulsions. Vomiting helps get rid of toxins, but it also throws away nourishment. Depression helps disconnect from maladaptive situations, but it also leads to social withdrawal and loss of initiative. Crying helps bring rescue from friends, but it also reveals your situation to potential enemies. So now it stands to reason that there will after all be benefits to getting better and costs to delaying cure. The moral is: sometimes it really is bad not to return to feeling good as soon as possible. And I have been discussing here only examples of self-generated defences. In cases where the sickness in question is a genuine defect or malfunction – a broken leg, say, or a snake bite or a cancerous growth – the balance of advantage must be clearer still. Surely in these cases there could be no advantage at all in withholding cure. Or couldn’t there be? • Costs of the process of cure as such When the sickness is self-generated, so that cure can be achieved simply by switching off whatever internal process is responsible for generating the symptoms in the first place, then, it’s true, the cure comes cheap – and there should indeed be little reason to hold back just on cost grounds. With pain, for example,