You may have missed out on love, transcendental oneness with the Universe, the adrenaline rush of the warrior, but you’ve had a headache or a bad back. Pain is the one engulfing, undeniable, incommunicable experience we’ve all had. And yet for all its ubiquity, pain is a solitary encounter, a lonely way of discovering the certainty that you exist. I hurt therefore I am is rapidly followed by I hurt therefore I am alone. Two people in pain are not nearly as likely to commit themselves to each other for life, or found a religious community, or become comrades in battle as they are to curl up silently in separate corners of the room to suffer alone what can’t be shared. Nasty business. One of the nastiest we can think of. Fear of death in a secular society is largely fear of pain. It’s not hard to imagine longing for death as a release from pain, but very difficult to believe one would wish to trade the blankness of death for living agony. Even self-confessed masochists are clear that the pain they want is the pain of their choosing, at the time of their choosing and with the sadist of their choosing, not an attack of toothache or appendicitis.
Yet masochism in some more general form must be implicated in the mysterious fact that the technology of pain relief has been so neglected by our pathologically innovative, life-improving species, which has always and everywhere suffered from it. We have developed as far as the pre-washed lettuce and the Flip-Down Magnifying Eye Make-Up Glasses (Innovations, £9.99), but can do nothing for your current migraine attack. Lurking somewhere is the belief that pain is good for you, and/or deserved, because pain as punishment and salvation is our cultural sine qua non. ‘Because you have done this ... I will greatly increase your pangs in childbearing; in pain you shall bring forth children,’ our first story tells us. And we are only to be redeemed through the agony of Christ’s crucifixion: a sharp blow to the back of the head or a firing squad just wouldn’t have done. Hold still, darling, while I pour iodine onto your cut, yes I know it stings, but that’s because it’s doing you good. Stop complaining, of course the poultice is unbearably hot: it won’t work otherwise. No pain, no gain. Feel the burn.
Actually, I’d rather not, and the blessed Patrick Wall, neuroscientist and pain doctor, wishes it to be known that pain is almost entirely useless and good for nothing but getting rid of. He cites cancer pain, with the impatience of one who is suffering it himself, as the apogee of pointlessness. Cancer only hurts once the tumour has grown large enough to become an obstruction or irritant. Before that, when something might be done about it, cancer grows in painless silence. Wall has no time for those who justify pain as a warning system.
Just about every high-school biology text contains a diagram where a finger touches a saucepan and is rapidly withdrawn. It is used to ‘explain’ pain as the method of avoiding injury run by a reflex mechanism consisting of sensory afferents which make motor nerves withdraw the hand. I despise that diagram for its triviality. I would estimate that we spend a few seconds in an entire lifetime successfully withdrawing from a threatening stimulus. Unfortunately, we are destined to spend days and months in pain during our lifetime, none of which is explained by that silly diagram.
Children born with the rare condition of congenital analgesia have no sensation of pain but rapidly develop strategies to avoid danger and rely on other symptoms to know that they’re ill: appendicitis is diagnosed by fever, inflammation and gut motility, danger is apprehended and learned through the alarm and teaching of others. It is a matter of tactics, which are themselves integral to the experience of pain, Wall suggests. The deep, spreading, sickening pain that follows the first intense stab of twisting an ankle serves to make the sufferer guard the wound against movement or pressure that would prevent repair. If they are bombarded with injury messages, the spinal-cord cells become hypersensitive and stimulate both biological repair systems and appropriate behaviour. Like children having their wounds kissed better, we can be distracted from the worst of pains, since attention is a major and early factor in its development. Pain even dismisses itself when there are more urgent priorities. The need to get away from danger, or towards safety, can put pain into abeyance: many soldiers wounded in battle do not feel pain until behind the lines. This isn’t heroism, which would require the pain to be felt and ignored, nor is it shock, at least not in the layperson’s sense, since that tells us nothing about the process. Wall describes with some relish the unpromising, unfancied racehorse, Henbit, accelerating away from the pack to win the Epsom Derby in 1980, not just in spite of, but because of breaking his leg in a stumble during the early part of the race. The horse only began to limp in the paddock. The fracture healed perfectly, but Henbit never outclassed himself again and was put out to stud. ‘Smart horse,’ says Wall.
How much pain people (and horses) feel depends on factors beyond mechanical damage, including their own and other people’s expectations. In an emergency room study of people who arrived in pain, Wall’s colleague Ron Melzack discovered that the complaints were assessed by the professionals as if there were objective and appropriate levels of pain. The emergency room staff thought that 40 per cent were making ‘a terrible fuss’, nearly 40 per cent were ‘denying’ pain, and 20 per cent gave an ‘appropriate’ answer. Clearly, Henbit was in denial. On the other hand, an Israeli Defence Force lieutenant who had one leg blown off during the Yom Kippur war by an exploding shell showed what might be thought of as appropriate signs of deep distress and tears, but when asked about the pain, replied: ‘The pain is nothing, but who is going to marry me now?’
Wall wants nothing to do with the distinction between bodily pain and anguish of mind. He puts the blame firmly on Descartes for our tendency to separate physical and mental pain. At a recent lecture, he showed the dreaded dualist’s picture of the pain pathway – an illustration from L’Homme – in which a stimulus of fire yanks on the pain cord that ends in the common sense centre in the pineal gland. ‘How silly it is and always was,’ he snapped, and surely the shade of Descartes shrank in shame. In his book, Wall gives the shortest of shrifts to the theory that divides the sensory system from the mental processing of received messages: ‘That route has been taken for two thousand years, from Aristotle to John Searle and Daniel Dennett. Pain has been used repeatedly as the simplest possible example of a physical stimulus which inevitably results in a mental response. We will not retrace this route, dropping the names of Bacon, Hume, Berkeley, Kant and Wittgenstein ... Nor will we join my fellow emeritus academics in their obsession to greet our oncoming senility with a discussion of consciousness.’ Asked at the lecture if he would like to comment on the role of consciousness in pain, he replied with a brisk ‘no’.
His reasons for such a curt dismissal are not merely ideological: they stem from a plainly humanitarian wish to rescue people in chronic pain from being labelled malingerers and neurotics just because their doctors cannot trace the pain directly to damaged tissue. Medical training still requires pain to be a symptom of a clear pathological process which it is the doctor’s job to cure. Dealing with symptoms has traditionally been passed down the hierarchy to nurses and physiotherapists, just as, historically, caring for the dying has not been seen as the concern of the doctor, who once he or she has established that no cure is possible perceives the patient as a failure. Wall’s forty years as a neuroscientist have left him with the conviction that a ‘hard-wired, line-dedicated, specialised pain system did not exist. Rather, there is a subtle multiplexed reactive system that informs us simultaneously about events in the tissues and in the thinking parts of the brain.’ What is obvious to him is that ‘the separation of sensation from perception was quite artificial, and that sensory and cognitive mechanisms operated as a whole.’
This hardly simplifies things, especially when the tricky business of the placebo effect is considered. No one likes the placebo effect. Drug companies have to prove their active chemicals are more efficient than a sugar pill that alleviates symptoms. Doctors fear they might turn out to be no more than the quacks they have been taught to despise. And patients, told that a blank tablet made their pain disappear, are not delighted to discover that they are suggestible, or even that their pain may have been as phantasmal as the cure. ‘I have responded to placebo trials myself,’ Wall writes, ‘and I am always mortified and ashamed of myself.’ But suggestibility and fantasy may have nothing to do with it. Using an ultrasound machine to massage the faces of people who had just undergone wisdom-tooth extraction gave as many patients relief from their pain when the machine was turned off as when it was on. What’s more, it reduced the symptomatic swelling of the jaw and improved the ability of patients to open their mouths, thereby matching in effectiveness a substantial dose of anti-inflammatory steroid. Well, wouldn’t you feel a fool?
Not if cultural and learned expectation were taken to be part of the account of pain. Young children do not respond to placebos as adults do, not having learned about the therapeutic effect of pills. Pharmaceutical companies have been quick to understand the power of expectation. A coloured tablet with corners is better than a round white tablet. The colour red is associated with power; green and blue with calm. Capsules containing coloured beads are better than any tablet, while an intramuscular injection is understood to be a much more serious therapy. At the top of the list is an intravenous injection – even of saline. That’ll sort it. According to Wall, one professor of medicine taught his students to give patients a tablet held in forceps while explaining that it was too powerful to be touched by fingers. Placebos work because we know that medicine works. Perhaps because we know a pill is likely to do us good, the natural endorphins kick in. When patients are given a narcotic antagonist, experimenters can no longer reduce their tooth-extraction pain with a placebo. But placebos do not work when given to a patient in secrecy. There must be some evidence of intended treatment. A patient is inclined to expect a beneficial effect with any kind of therapy. ‘The placebo is not a stimulus but an action which experience has taught may be followed by relief.’ A degree of optimism is needed, however. Tests by clinical psychologists to prove that placebo responders were hysterics, neurotics, unusually suggestible or introspective, showed none of these traits to be diagnostic of a good response. Depressives, however, are poor responders, because, after all, low expectation is in the nature of depression. ‘Avoid pessimists if you are looking for placebo reactors,’ Wall warns.
Isn’t there something worrying here? The placebo effect is getting to be quite old news. Surely, the more word gets out that snake oil works as well as serotonin reuptake inhibitors the less effective the effect will be? If the doctor might as well hand you a pill made of talc instead of some chemical worth more than its weight in gold, why wouldn’t she? And once you’ve had that thought, what’s to stop an outbreak of reverse placebo action, and the general inhibition of a positive response even to active medicines? There is such a thing as a nocebo effect: it’s what you get when you look at the leaflet that comes with your pills telling you of possible side-effects. In any case, the nocebo effect works the same way as a shaman’s death curse. Perhaps it’s best not to think too much about it. Would we, knowing what we know about the placebo effect, be astonished to learn that Prozac or Viagra or some new miracle migraine relief were in fact placebo experiments on a worldwide scale? Don’t say you haven’t been warned.