The Placebo Effect: The Power of Nothing
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THE POWER OF NOTHING
New Scientist Magazine
26 May 2001
Want to devise a new form of alternative medicine? No problem. Here's the
Be warm, sympathetic, reassuring and enthusiastic. Your treatment should
involve physical contact, and each session with your patients should last at
least half an hour. Encourage your patients to take an active part in their
treatment and understand how their disorders relate to the rest of their
lives. Tell them that their own bodies possess the true power to heal. Make
them pay you out of their own pockets. Describe your treatment in familiar
words, but embroidered with a hint of mysticism: energy fields, energy
flows, energy blocks, meridians, forces, auras, rhythms and the like. Refer
to the knowledge of an earlier age: wisdom carelessly swept aside by the
rise and rise of blind, mechanistic science.
Oh, come off it, you're saying. Something invented off the top of your head
couldn't possibly work, could it? Well yes, it could--and often well enough
to earn you a living. A good living if you are sufficiently convincing or,
better still, really believe in your therapy.
Many illnesses get better on their own, so if you are lucky and administer
your treatment at just the right time you'll get the credit. But that's only
part of it. Some of the improvement really would be down to you. Not
necessarily because you'd recommended ginseng rather than camomile tea or
used this crystal as opposed to that pressure point. Nothing so specific.
Your healing power would be the outcome of a paradoxical force that
conventional medicine recognises but remains oddly ambivalent about: the
Placebos are treatments that have no direct effect on the body, yet still
work because the patient has faith in their power to heal. Most often the
term refers to a dummy pill, but it applies just as much to any device or
procedure, from a sticking plaster to a crystal to an operation. The
existence of the placebo effect implies that even quackery may confer real
benefits, which is why any mention of placebo is a touchy subject for many
practitioners of complementary and alternative medicine (CAM), who are
likely to regard it as tantamount to a charge of charlatanism. In fact, the
placebo effect is a powerful part of all medical care, orthodox or
otherwise, though its role is often neglected and misunderstood.
One of the great strengths of CAM may be its practioners' skill in deploying
the placebo effect to accomplish real healing. "Complementary practitioners
are miles better at producing non-specific effects and good therapeutic
relationships," says Edzard Ernst, professor of CAM at Exeter University.
The question is whether CAM could be integrated into conventional medicine,
as some would like, without losing much of this power.
At one level, it should come as no surprise that our state of mind can
influence our physiology: anger opens the superficial blood vessels of the
face; sadness pumps the tear glands. But exactly how placebos work their
medical magic is still largely unknown. Most of the scant research to date
has focused on the control of pain, because it's one of the commonest
complaints and lends itself to experimental study. Here, attention has
turned to the endorphins, natural counterparts of morphine that are known to
help control pain. "Any of the neurochemicals involved in transmitting pain
impulses or modulating them might also be involved in generating the placebo
response," says Don Price, an oral surgeon at the University of Florida who
studies the placebo effect in dental pain. "But endorphins are still out in
That case has been strengthened by the recent work of Fabrizio Benedetti of
the University of Turin, who showed that the placebo effect can be abolished
by a drug, naloxone, which blocks the effects of endorphins. Benedetti
induced pain in human volunteers by inflating a blood-pressure cuff on the
forearm. He did this several times a day for several days, using morphine
each time to control the pain. On the final day, without saying anything, he
replaced the morphine with a saline solution. This still relieved the
subjects' pain: a placebo effect. But when he added naloxone to the saline
the pain relief disappeared. Here was direct proof that placebo analgesia is
mediated, at least in part, by these natural opiates.
Still, no one knows how belief triggers endorphin release, or why most
people can't achieve placebo pain relief simply by willing it. Several labs
are now thinking of using brain imaging to study the neurobiology of the
placebo effect in more detail. "The brain has already been imaged during
drug-induced analgesia," says Price. "There's going to be a race between
laboratories to do this experiment first for placebo analgesia."
Though scientists don't know exactly how placebos work, they have
accumulated a fair bit of knowledge about how to trigger the effect. A
London rheumatologist found, for example, that red dummy capsules made more
effective painkillers than blue, green or yellow ones. Research on American
students revealed that blue pills make better sedatives than pink, a colour
more suitable for stimulants. Even branding can make a difference: if Aspro
or Tylenol are what you like to take for a headache, their chemically
identical generic equivalents may be less effective.
It matters, too, how the treatment is delivered. Decades ago, when the major
tranquilliser chlorpromazine was being introduced, a doctor in Kansas
categorised his colleagues according to whether they were keen on it, openly
sceptical of its benefits, or took a "let's try and see" attitude (American
Journal of Psychiatry, vol 113, p 52). His conclusion: the more enthusiastic
the doctor, the better the drug performed. And this year Ernst surveyed
published studies that compared doctors' bedside manners (The Lancet, vol
357, p 757). The studies turned up one consistent finding: "Physicians who
adopt a warm, friendly and reassuring manner," he reported, "are more
effective than those whose consultations are formal and do not offer
Warm, friendly and reassuring are precisely CAM's strong suits, of course.
Many of the ingredients of that opening recipe -- the physical contact, the
generous swathes of time, the strong hints of supernormal healing power --
are just the kind of thing likely to impress patients. It's hardly
surprising, then, that complementary practitioners are generally best at
mobilising the placebo effect, says Arthur Kleinman, professor of social
anthropology at Harvard University.
"This doesn't go down well in these communities because of the denigrating
connotations of placebos. It's very threatening to people in those fields,"
Kleinman says. "The problem is that biomedicine has an extraordinarily
negative view of placebos. They're treated as a nuisance rather than being
seen as what they really are." And what they are, according to Kleinman, is
part of the complex interaction of physiology, psychology and culture which
underlies the process of turning a sick person into a healthy one.
This, needless to say, is a world away from the mechanistic approach of most
conventional medicine, which has little to say about what people's
experience of illness means to them. As Ernst puts it: "The very popularity
of complementary medicine is a criticism of mainstream medicine. In the
mainstream we have sharper and sharper tools. But in terms of empathy, time,
understanding and touch we are losing out."
But even if many CAM therapies do get much of their power from the placebo
effect, it's still important to ask whether there's anything more to them
than that. To say -- as many a CAM practitioner does -- that a treatment
"works" begs the question of how well it works. If a mantra-induced placebo
effect will ease the pain of my bad back, that's good. But might something
else do it even better? A handful of aspirin, for example? If doctors had
been content to declare that a treatment works and leave it at that,
orthodox medicine would not have got far. We want to know not just what
works, but what works best. In answering that question, there's no
substitute for clinical trials.
Yet it's not easy to design those trials in a way that both CAM advocates
and conventional scientists will agree is fair. To give the clearest
possible test of the treatments in question, experimentalists want to
randomly assign patients to receive, say, aspirin or mantra therapy while
rigorously holding all other conditions constant. But CAM practitioners
charge that this cookie-cutter regularity is unfair to CAM therapies because
it removes the individualised care that is such a central feature of most of
them. "Because I apply orthodox research methods to complementary medicine,
I've been accused of stripping it of what makes it work," says Ernst. "They
say I'm throwing out the baby with the bath water. I accept that this could
be a danger. If a therapy works only as a placebo then maybe one should keep
science out of it. On the other hand this is how science advances."
This problem of context extends far beyond the realm of research. It also
casts a shadow over attempts to integrate alternative therapies, with their
powerful placebo-invoking techniques, into mainstream medicine. In practice
this integration would mean, among other things, offering alternative
medicine on state systems like Britain's National Health Service. To a
limited but growing extent this already happens: the NHS runs a couple of
homeopathic hospitals, and increasing numbers of family doctors invite
aromatherapists, acupuncturists, herbalists and others into their surgeries.
Some doctors even administer these treatments themselves.
But for much of CAM--especially techniques in which the placebo effect
accounts for most or perhaps all the benefit--integration might well be
counterproductive. After all, the value of CAM depends partly on its
unorthodoxy. Price talks of a "clash of cultures". Would your free,
state-registered crystal therapist, pressed for time and perhaps wearing a
uniform just like other paramedical staff, still be able to mobilise as good
a placebo response? Ernst, for one, doubts it, and sees this as a powerful
argument against integration. "Although there is little evidence to support
the view, one intuitively feels that something exotic has a stronger placebo
effect than something bog standard. And some complementary therapies are
very exotic," he says.
Integration faces other obstacles, too. Doctors would face serious ethical
problems in recommending what they know to be placebo treatments to their
patients (see "An ethical dilemma" below). And complementary practitioners
would likely be disparaged by their conventional counterparts, as they often
are today. With the growing emphasis on evidence-based medicine, installing
a roomful of radionics boxes or setting aside a clinic for dispensing Bach
flower remedies would be hard to justify, however much it might please the
customers. Integrated medicine "would have about as much validity as a
hybrid of astronomy and astrology", Neville Goodman, an anaesthetist in
Bristol, wrote in the April newsletter of HealthWatch.
Healthcare managers, too, may view such moves with some alarm. The addition
of a whole raft of new and time-consuming treatments could play havoc with
already overstretched budgets. In the long term, though, a few CAM
techniques might achieve integration. A study of low back pain by Britain's
Medical Research Council, for instance, revealed that chiropractic compares
favourably with conventional hospital treatment in terms of cost and
effectiveness (British Medical Journal, vol 300, p 1431). It's likely that
chiropractic treatment provides specific benefits over and above the placebo
Even CAM techniques that do largely depend on their placebo value could
achieve the same cost-effectiveness. Indeed, for most of medicine's history,
compassion, attention and tender loving care -- all big contributors to the
placebo effect -- were all that doctors had to offer. The advent of science
changed that, but in adopting their new role of body technician, doctors
have to a great extent dropped the traditional one of healer: the
non-specific but still valuable business of caring. Most doctors would now
be faintly embarrassed by the suggestion that "healing" might be part of
their job description. It sounds a bit pre-scientific. But that's what most
CAM practitioners still offer, and they are certainly not embarrassed by the
A professor of surgery with a confident manner, an expensive suit and an
international reputation who sees you privately and guarantees to solve your
problem with a costly operation may still be unrivalled as a source of
placebo power. But most doctors are beaten hands down by countless
alternative practitioners who might not know a lymphocyte from a lump of
cheese. What they do know is how to make you feel better. And that's a big
part of the battle.
AN ETHICAL DILEMMA
For doctors who take their medical ethics seriously, the placebo effect can
pose a dilemma. Imagine that a patient turns up asking asking for advice
about a remedy which is harmless but, in the doctor's view, also useless. If
there's a proven orthodox cure for the complaint, the correct course of
action is clear: steer the patient towards that treatment.
But suppose there is no orthodox treatment, or the patient has tried
whatever there is and not responded. Should the doctor stay true to science
and declare that the remedy is a waste of time, thereby undermining any
beneficial placebo effect it might have? Or should scientific purity be
sacrificed in favour of an enthusiastic but dishonest endorsement which
might boost the treatment's placebo action? Could the doctor even argue that
endorsement would be legitimate because the remedy would in fact have some
benefit, thanks to the placebo effect?
In practice, many doctors try to avoid betraying either their allegiance to
science or their ethical duty to tell the truth. One escape route is to find
a form of words which wriggles round the problem. Something like, "I've had
no first-hand experience of this treatment, but I know that some people find
it rewarding." That's what you call the art of medicine.
Geoff Watts is a medical and science journalist, and author of Pleasing the
Patient, a book on the placebo effect. He is also vice-chairman of the group
HealthWatch, which argues the case for reliable information about medicine
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