A placebo is relief from belief: people often feel better simply because they believe they have been treated. More precisely, it is the appearance or illusion of a treatment effect that is not actually attributable to a biological treatment mechanism. Placebo effects can be downright bizarre, and they can seem almost miraculous in the right circumstances. Human beings will get great placebo from any treatment that seems impressive in any way (more invasive, novel, unpleasant, whatever suggests potency). This accounts for most treatment success stories from both patients and professionals. Interesting stuff — and you can read an overview of placebo like this on almost every health blog on the Internet.
Now for the bucket of cold water available only here (and a handful of other places):
Placebo gets more love than it deserves. I am interesed in the biology and psychology of placebo, but it is not a magical mind-over-matter phenomenon, or even a good consolation prize when treatment is otherwise ineffective. Many medical problems are entirely immune to positive thinking and expectation (try treating tuberculosis with a sugar pill and see how many Nobel Prizes you pick up for that innovation). The power of belief is strictly limited and accounts for only some of what we think of as “the” placebo effect. There are no mentally-mediated healing miracles. But there is an awful lot of ideologically motivated hype about placebo…
There is an annoying trend in alternative medicine: the aggrandization of “the power of placebo” as a justification for therapy that can’t beat a placebo. Therapies that perform no better than placebo are now predictably spun as being “as good as placebo,” as though placebo is the new gold standard to meet. Acupuncture is the most glaring example of this,1 but we’ve seen a lot of it with homeopathy as well.
The absurdity of this inflation of the placebo currency becomes clear with a simple comparison: would you take a drug that had been proven to be “as good as a placebo”? Not a chance! We expect real medicine to be significantly more effective than fake medicine. If Big Pharma tried to get away with touting a drug that way, they’d be … well, I guess they’d be even more hated and criticized than they are already are.
Placebo has been hijacked and re-branded for its public relations value to alternative medicine. If your treatment isn’t evidence-based, no worries: you can still sell the power of placebo!
Placebo often gets hyped as a defensive reaction to negative trial results in general, by any kind of health care professional wondering if evidence-based medicine might just put them out of business.
For example, in 2001, the infamous Philadelphia Panel on rehabilitation interventions showed that many popular treatments cannot beat a placebo,2 an evidence-based bummer of epic proportions. Physical therapist Carol Davis found this “shocking in many ways” and wrote a letter to the editors of Physical Therapy.3 Like so many others, before and since, her reaction was to blunt the bad science news by putting placebo on a pedestal and moving the goalposts of science, suggesting that controlled trials aren’t so great. The editors’ reply was perfect:
If Dr. Davis believes that our future as a profession lies in our ability to produce placebo effects, perhaps she misses the point. Her view taken to its logical conclusion would not mean that we could, as she said, “reduce the musculoskeletal curriculum by two thirds,” but rather that we could possibly eliminate this aspect of the curriculum in its entirety as we become not physical therapists but rather practitioners of “placebo enhancement.” As a curriculum coordinator, Dr Davis should know that this role is not what sets us apart from other practitioners and is not seen as our raison d’être in any practice act or in any document that describes our practice. I believe Dr Davis’ views to be unwise and reckless and, most importantly, potentially injurious to those patients who expect us to have some basis in science for our practice.
That was a strong condemnation. It’s a bad idea — “Unwise and reckless … potentially injurious …”! — to try to move away from controlled trials as the gold standard for figuring out what works. Let’s go where the evidence takes us. Let’s abandon what doesn’t work better than placebo, and find out what does.
This video presents a perspective on placebo that doesn’t worship the “power” of placebo, but looks instead at the paradox of placebo: if placebo is so powerful, why isn’t everyone cured? Because the placebo effect is basically a dysfunctional mistake.4 How refreshing!
It’s always called “the” placebo effect, but placebo is not just one thing. The term is almost hopelessly imprecise. It is actually category of phenomena, many of them clinically meaningless.5 We truly need to learn and use more precise terminology. It’s not just word-nerd nitpickery! Speaking only of “placebo” is about as useful as saying only “furniture” when you mean “chaise longue” or “credenza” or “futon.”
There are many ways for the appearance or illusion of a treatment effect to occur, “a wide variety of mechanistically different and likely experimentally distinct factors, including but not limited to bias, natural history, analysis errors, and regression to the mean.”6 Some of those illusions are biologically interesting, but many are not. For instance, a placebo effect may occur due to illusions and distortions in data collection and reporting — almost embarassingly trivial and boring factors, like regression to the mean or comparing endpoints to baseline instead of to inert treatment.7 Paperwork placebo!
Another example: being better is not equivalent with actually feeling better, and feeling better is not the same as saying you feel better. People can and do say things that don’t accurately represent their internal experience. A classic example is doctor-pleasing exaggeration of benefit. Placation placebo!
These complexities of human psychology and behaviour are why researchers often look at placebo effects as an annoyance: they are irritating distractions in research, and difficult to eradicate. There are myriad ways in which both treatment and placebo effects may not be what they seem. A placebo might be an interesting mind-powered effect on biology … or it might just be a statistical mirage! And that is what the evidence shows: that placebos do not have important clinical effects in general.8 Here’s a good example…
In the summer of 2011, I published a large article picking apart and translating an important new study of massage for low back pain. It contained an exciting and profound example of just how boring and trivial placebo effects can be. That’s right: boring and trivial. Not “powerful.”
Some patients got free massage therapy and their results were compared to patients who got no free massage. The massaged patients seemed to have significantly less pain after 10 weeks. But there was a serious flaw: the deprived patients knew they weren’t getting free massage. And that was almost certainly a disappointment to them, what is cutely referred to as a “frustrebo” effect.9 And that probably slanted the results.
The authors acknowledged that this flaw may actually have made massage “seem more superior than it really is” in comparison to the artificially negative results of the unmassaged patients. Scientific data that creates a false impression of reality is called a research artifact and this is a whopper, nasty and misleading. Lesser glitches have been the downfall of much bigger science. This kind of thing is exactly why “Why Most Published Research Findings Are False.”10
What we ended up with here was an appearance of a treatment effect in the difference between what may be genuinely therapeutic results on one side of the gap, and completely meaningless bias on the other. This is a perfect example of a placebo effect that is partly due not to the power of the mind, but to the power of an unfair comparison.
Just because a published paper presents a statistically significant result does not mean it necessarily has a biologically meaningful effect.
Science Left Behind: Feel-Good Fallacies and the Rise of the Anti-Scientific Left, Alex Berezow & Hank Campbell
It is possible that every stitch of apparent massage benefit in the Cherkin study was attributable to real changes in the physiology of those patients, but that is unlikely. It was probably a complicated mix of real benefit and research artifacts.
At least some of the benefits were due to the limited power of mind over body, stimulated by the inherently pleasing nature of masssage as an experience and resulting in genuinely improved symptoms (subjective experience) — and we should certainly not throw that baby out with the bathwater. And some of the apparent benefits were probably due to simply being happier and more confident (reporting artifact). And then some more of the apparent benefits were almost certainly due to the fact that not being massaged just looked rather bad by comparison, causing patients to actually feel a little worse (subjective experience) and report their experience more negatively (reporting artifact).
The appearance of a positive effect of massage here is greatly watered down by the unfair comparison, and definitely not just the “power” of mind over matter. The point is that it would be absurd to conclude from this data that massage “works” by the power of placebo.
So what is a myth in medicine? It is not everything that is false, but rather concepts that are based on something akin to a story. It is a good story that meniscal tears cause pain and that when they are removed, the pain goes away as well. Showing that pain relief is mainly due to placebo effects means destroying a good story, which might be as unpopular as depriving some colleagues of a good business.
Mythbusting in Orthopedics challenges our desire for meaning, by Per Aspenberg, 547
One of the greatest placebo hype examples to date was a 2010 study which purportedly proved that the power of mind over body is so stupendous that a placebo — a fake medicine, a sugar pill — works even when you know it’s a placebo.11 This has been uncritically reported and passed along by pretty much everyone, including a great many people who should probably know better. ScienceBasedMedicine.org published the only critical analysis I’m aware of, by Dr. David Gorski, and he nails it:
Even though they did tell their subjects that the sugar pills they were being given were inert, the investigators also used suggestion to convince their subjects that these pills could nonetheless induce powerful “mind-body” effects. In other words, the investigators did the very thing they claimed they weren’t doing; they deceived their subjects to induce placebo effects.
In other words, can you “impress” patients into feeling better? Hey, maybe! Is it a non-deceptive placebo if you do it by saying “this fake medicine is really awesome”? Is it a non-deceptive placebo if you do it by saying “this fake medicine is really awesome”?No. That’s just a regular placebo — very old school. There’s really nothing new here. It’s not placebo “without deception,” but placebo with deception about the value of placebo itself.
The lead author, Ted Kaptchuk, is transparently aggrandizing placebo, expanding its definition in a way that would (just coincidentally!) make it seem more magical and awesome — thus reinforcing his own story. “This fake medicine is really awesome as proved by studies like mine showing that this fake medicine is really awesome as proved by studies like mine showing …”
As predicted,12 Kaptchuk is continuing to tell this story with a new study in 2016, this time concerning back pain.13 Dr. Gorski has again done the Yeoman’s work of deconstructing the placebo propaganda, with a new article, “The revenge of the son of the myth of ‘placebos without deception’,” in which he makes it clear that this new study is even more ridiculous than the last one:
Right off the bat the investigators recruited patients who were interested in “mind-body” effects and then told them that placebo effects could produce powerful “mind-body self-healing processes” in rigorous clinical testing. There was the deception, because even the most generous and sympathetic characterization of the rigorous research existing on placebo effects would not justify such a description. As I said at the time, not only did Kaptchuk et al deceive their subjects to trigger placebo effects, whether they realized or would admit that that’s what they did or not, but they might very well have specifically attracted patients more prone to believing that the power of “mind-body” interactions. Yes, patients were informed that they were receiving a placebo, but that knowledge was tainted by what the investigators told them about what the placebo pills could do.
This is essentially propaganda research, producing results to be used to try to shore up alternative medicine’s credibility as it gets backed further into a scientific corner. As study after study shows that treatments like homeopathy and acupuncture are no better than a placebo — a slam dunk fail — many beleaguered proponents have stopped trying to deny it and have pivoted to spinning it as good news:
[They] start arguing that they “work” by “harnessing the power of placebo” effects to “induce natural healing,” misrepresenting placebo effects as the power to use one’s mind to heal oneself. Never mind that this argument never flies with conventional science-based medicine and represents a flagrant double standard in which CAM is held to a much lower standard of evidence. Again, this is about belief, not evidence. Never mind that lying to patients to invoke placebo effects is the resurrection of medical paternalism.
In 2015 Tuttle et al. reported on a bizarre thing: placebo response in trials of pain-killers seems to be growing.14 This finding got a lot of attention, and added to placebo hype and mystique.
But let’s be very clear that this study raised more questions than it answered, and probably the only implication you can take to the bank is that “it is yet more evidence that placebo effects are complicated and are largely due to artifacts in the way clinical trials are designed and executed” (Dr. Steven Novella). And Dr. David Colquhoun seems to think the whole business is a tempest in a teapot (and he’s as authoritative on the subject of placebo as anyone has ever been):
I find the arguments in this piece quite baffling. If a treatment does not perform better than a dummy placebo, then it doesn't work. The trial is not thwarted by the placebo response: it has answered the question that was asked, even if the answer is a disappointing one. It is also not right to refer to responses that are observed in people who are given a dummy pill as a placebo response. The changes seen in the dummy group are a combination of placebo response and regression to the mean (roughly. the get-better-anyway effect). There is an increasing body of evidence that the latter is more important than the former. Placebo effects, though real, are generally too small in size to be of noticeable benefit to patients.
Placebo is interesting, but not nearly as interesting as most people seem to think these days, and as a general rule they are nowhere near powerful or consistent or “real” enough justify deliberate prescription (lying to patients), or as a reason to continue using treatments that are otherwise proven to be ineffective or barely effective. Placebo, in short, is not therapy. Kaptchuck et al. — and many others — exaggerated both the certainty and the therapeutic potential of placebo to his study subjects, so it’s hardly surprising they responded more strongly. Placebo effects are actually quite erratic, small, transient, and conspicuously absent entirely for many pathologies. Try telling patients that about their sham medication and see how well it works.
Justified, rational reassurance is still the only ethical way to persuade/condition a patient into experiencing some interesting mind-over-matter effects — which is practically the mission statement for this website. I am devoted to explaining common pain problems, not fluffing up the value of unproven therapies. Dr. Harriet Hall in Benedetti on Placebos (an excellent read):
Prescribing placebos is uniformly rejected by medical ethicists: instead, we can put our increasing knowledge of placebo neurophysiology to good use without lying to patients.
And Drs. Silvernail and Ingram, physical therapists (Ingram et al):
We need to work harder to understand and communicate the basic science of our profession. This focus should naturally cause us to consider prior plausibility more strongly when deciding which interventions and concepts to include in our therapeutic process.… We feel strongly that our patients deserve scientically defensible care that is more than just artfully delivered placebo.
Placebo is not only not as potent as popularly imagined, but it can also backfire quite badly.
Reminder: even researchers with a clear pro-acupuncture agenda have prominently conceded that acupuncture is no better than a placebo, but then go right ahead and daftly and paradoxically recommended it anyway … you know, for the sake of a good placebo effect.15 Not only did Berman et al recommend it, they advised doctors to send patients to a “properly trained” acupuncturist.
Properly trained how, exactly? In placebo delivery? At the point of a needle. We live in an age of such vigorously defended patient rights and robust anti-paternalism that it’s ethically verboten for doctors to prescribe so much as a sugar pill. And that’s (mostly) a good thing. But these pro-acupuncture doctors think it’s okay to send you to a “properly trained” acupuncturist for $1000 worth of placebo-inducing ritualistic needling?16
It’s not just about the pointless expense.17
When I was a massage therapist, I routinely saw significant harm done by acupuncture and other ineffective therapies. Far from enjoying a robust mind-over-matter placebo effect, most patients seemed to believe all the more in their back pain as an unassailable affliction that “even acupuncture” couldn’t help.
More tragic than simply wasting time and money on a treatment that doesn’t work is that so many patients conclude not that the treatment was ineffective but that acupuncture was defeated … defeated by an unusually serious case of back pain. Everything placebo can do, nocebo can do … in the other direction.Patients are strongly predisposed to anxious assumptions that their problem is “really bad,” and the failure of acupuncture confirms it. The acupuncturist is given the benefit of the doubt, while their back pain is elevated to the status of a fiercer enemy. A nice trap.
How’s that for a “placebo”? In fact, that’s a kind of nocebo, the anti-placebo, where perception and belief result in a negative effect instead of a positive one. Everything placebo can do, nocebo can do … in the other direction. But you never hear freelance alt-med therapists talking up the “power of nocebo” or worrying about giving their patient anxiety-producing notions about what might or might not be wrong with them. They should be, but they don’t.
The scientific evidence is overwhelming that emotional and psychological factors are of real importance in low back pain (and many other kinds of chronic pain). The pain is not “all in your head,” but it is affected by what’s in your head. The despair that sets in when a minor placebo effect wears off is really problematic, significantly exacerbating people’s fear that they are “screwed.” Thanks, acupuncture! Thanks a bunch.
It seems to me that placebo treatments ought to be paid with a placebo payment.
Even when people begin to accept that a treatment is probably bunk — homeopathy is a good example — they often still protest that they are happy to pay for a placebo. As long as it works, who cares how? And placebo can work! So why not? This is basically the medicinal version of Pascal’s wager (erring on the side of faith). If the stuff actually works, great. If not, at least there’s the placebo consolation prize.
I have no problem with people paying for a placebo as long as their eyes are wide open. But … the wider your eyes get, the less likely you are to benefit from a placebo (despite the “open label” hype, see above). And there are very strict limits to what placebo can do … and paying for things is never completely harmless, because that money could be used for other things … and trying to use a placebo gets a lot more problematic when something really medically serious comes up.
Where I have the least objection to “paying for a placebo” is for treatments in the gray zone: unknown efficacy but some plausibility and low risk. I’ve tried many such treatments, knowing full well that any effect I enjoy is probably just placebo (or regression to the mean, or natural recovery)… but it might be an actual effect, and I’m willing to pay a little for that chance. But, for me, the plausibility has to be there.
It ain’t there with homeopathy. And lots of other things where people are banking on getting at least a placebo.
I am a science writer, former massage therapist, and I was the assistant editor at ScienceBasedMedicine.org for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.
— Science update: coverage of another round of nonsense about “placebos without deception.”
— New section: “Is it okay to pay for a placebo?”
— New section: “Is the placebo effect getting stronger? The Tuttle kerfuffle”
See also:BACK TO TEXT
Humphrey and Skoyles proposes an evolutionary explanation for the placebo paradox: even though it might be possible in theory, in practice our brains dare not routinely invoke powerful recovery mechanisms because they have costs that often outweigh the benefits. Here’s some excellent some extra reading from Todd Hargrove, who did a nice job interpreting and explaining this idea. The additional perspective is most welcome.BACK TO TEXT
Harriet Hall translated this French article on placebo for ScienceBasedMedicine.org, calling it “the best explanation of placebo that I had ever read.” (I was quite involved editorially, and in particular spent a bunch of time on producing shinier, translated diagrams.) I’m not quite sure it’s the best placebo explanation I’ve ever read, but on the other hand I can’t point to a better one, and it is certainly chock-a-block with historical context, effectively cited science, and little gems of clarity on this tricky topic. The gist of the article is that “placebo” is an umbrella term for many phenomena, most which are relevant only to research methodology, not treating patients.BACK TO TEXT
The nugget of this large review of placebo effects: “We did not find that placebo interventions have important clinical effects in general.” And, particularly pertinent to this website, “The effect on pain varied, even among trials with low risk of bias, from negligible to clinically important.” This is consistent with my position that placebo is far from “powerful,” but may have a strong impact on pain in ideal circumstances. As Dr. Steven Novella summarized it, “In other words, the best research we have strongly suggests that placebo effects are illusions, not real physiological effects.”BACK TO TEXT