Just How Much Power Does the Mind Have to Heal the Body?

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Photo: Chris Parsons/(c) Chris Parsons

The idea that the mind can exert healing powers over the body is one that is most often associated with pseudoscience — and, usually, justifiably so. Cancer patients can’t think their way to healthy; depression doesn’t work like that, either. 

But, on the other hand, consider the placebo effect and the subjective improvement in symptoms people report after taking bogus drugs. Clearly, the mind and body work in tandem when it comes to our experience of some physical ailments — but which ones, and to what extent?

In a new book Cure: A Journey Into the Science of Mind Over Body, science writer Jo Marchant takes on this question, exploring the ways many scientists are now attempting to harness the placebo effect to improve patient care. Marchant is a skeptical, evidence-based reporter — one with a background in microbiology, no less — which makes for a fascinating juxtaposition against some of the alternative treatments she discusses. She spoke recently with Science of Us about the very real physiological and biochemical changes that can occur in the brain and body as a result of some totally fake treatments.

This idea you’re talking about here — about the mind’s capacity to promote actual, physical healing in the body — is, on the one hand, undeniably fascinating. But at the same time, it walks pretty uncomfortably close at times to claims that sound a lot like pseudoscience. So what made you want to take on this subject?
I think maybe it is the fact that it walks so close to pseudoscience that made me really interested. Because, on the one hand, it’s common sense that the mind and the body interact with each other. We’re all familiar with that in so many ways: If you’re narrowly hit by a car, for example, you can feel your heart pumping. All the time we are experiencing how our mental states affect our physiology — that’s very clear.

But when it comes to health, suddenly there are all these controversial questions. You get all these claims from alternative therapists that the mind can heal us and can cure cancer or can supposedly heal someone’s paralysis after they’ve broken their neck — you know, these ridiculous claims. And yet on the other hand, you have skeptics who have dismissed the idea that the mind plays any role in health, who call the whole thing quackery.

So I was interested in why we find it so hard to have reasonable debates about this question. And I was interested in where that comes from, so I wanted to look at the evidence myself, in a sort of critical but open-minded way to see what the evidence really says.

Did you get a sense from your research of the reason why some of us, perhaps especially those of us in Western society, do tend to think of the mind and the body as these very discrete entities?
There are lots of things feeding into it, going back centuries, really. A lot of people talk about the philosopher Descartes as coming up with this original division between the mind and the body. He saw a difference between the physical, measurable matter — which was suitable for being studied in a scientific way — and the immeasurable, temporal soul or spirit, which couldn’t be studied in that way. Now, of course, today the idea that we may be influenced by some soul floating in our heads isn’t really the world that we’re living in, and many scientists do understand the idea that our bodies may be influenced by a certain configuration of neurons in our brains.

But there’s still the hangover from that sort of way of thinking about the mind and the body as two different things, of thinking of the mind — of emotions and feelings — of being less real, and therefore an unsuitable topic for scientific research. You take a study where the outcome is patients’ self-report of pain, for example. That’s often seen as not as rigorous as a study that began with a physically measured parameter or test.

There’s also the fact that we now rely on clinical trials, and we test drugs and treatments against placebo. It’s pretty important, of course, to see that our drugs and treatments really do work, and that we’re not being fooled by the placebo effect. But at the same time, that puts all the focus onto the direct physical effects of those drugs and treatments. It kind of cancels out the other things — things like our expectations or the social interaction in treatment. These are things that can affect how we do as patients, but they kind of get sidelined and ignored, because we don’t have a way to measure them.

When people refer to a “placebo effect,” they’re often implying that people are essentially being fooled. But that’s not what you’re saying in your book. 
So the phrase “placebo effect” is often used in a different way by the public, and I think that’s where a lot of this disagreement comes from. So one thing that it can mean is simply in a trial where one group gets a drug, and the other group gets a fake drug, a placebo. The placebo effect there just refers to any improvement that you see in that trial. And there can be a lot of different reasons behind any improvement that you see — a lot of those people maybe would’ve improved anyway, regardless of what they took. Or, just statistically, people’s symptoms can fluctuate.

But what scientists are finding is that in addition to those sorts of nonspecific effects, taking a placebo also has real, measurable, biological effects on the brain and body — similar to the effects caused by drugs. So that’s kind of another meaning to “the placebo effect” — it’s specifically talking about these changes.

And that’s what’s surprising about these effects — people often think if you take a placebo to relieve your pain, for example, that that’s sort of an imaginary effect. It’s just a change in perception — maybe you just thought you were in pain when really you were not. But what neuroscientists are finding are these real, biological changes that can be measured.

For example, a placebo painkiller can trigger the release of endorphins in the brain. And these are actual pain-relieving chemicals — they’re actually what pain-relieving drugs like morphine are designed to release. So the placebo painkiller is actually working through the same biochemical pathway as the drug is. Parkinson’s patients, if they receive a placebo drug, will get a release of the neurotransmitter dopamine in the brain, which is what happens when they take their real drugs. In each of these cases, you’re seeing biochemical changes that are actually very similar to the pathways that are employed by drugs.

So then what does this tell us about measuring the efficacy of drugs against a placebo? I’m thinking specifically here about flibanserin — you know, “lady Viagra” — which was shown in clinical trials to have effects that were just barely perceptible over a placebo.
Yeah, it gets quite tricky, doesn’t it? Placebo-controlled trials, what they were designed for is testing the direct effect of a drug or treatment, so you’re comparing it against a placebo. Which is great if what you’re testing is a drug. But if you want to test other things, like how our minds are influencing our symptoms or our health, these trials are really not so appropriate.

So, for example, acupuncture. If you test acupuncture in trials against sham acupuncture, which is where the needles are put in the wrong places and they don’t properly penetrate the skin, there’s generally no significant difference between those two things. So that is generally used to prove that acupuncture doesn’t work — that it’s worthless.

But there was a very interesting trial in Germany, in more than a thousand patients with chronic back pain. And there were two groups: One got acupuncture, and one got the fake acupuncture. But then there was a third group, which was given conventional treatment for their pain — so that was a combination of painkillers, physiotherapy, and exercise. And those patients who got conventional treatment did barely half as well as those who got the acupuncture. So even though acupuncture was no better than placebo, it was still a lot better than the drugs.

And it’s because there are all these other components that go into the treatment: the ritual, the hope, the expectations, the social interaction. Because of all those things, it can actually mean that even if something has no actual effect at all — like acupuncture — it can still be better for patients in some senses than the drugs.

So I think we need to really think, in some cases, how we’re designing those trials, to make sure that we really capture all those effects.

But there are certain kinds of conditions that respond to placebo treatments and kinds that do not. Can you give some examples?
Obviously, if you’ve got a life-threatening condition such as cancer, positive thoughts are not going to heal your cancer. You’re going to need conventional treatment. It can help you cope with the symptoms; therapy might help somebody to stick to their chemotherapy regimes, which can be very difficult. So I think there can be a role for the mind to play, even in these serious, life-threatening conditions. But it’s not going to cure your underlying disease.

And there are some other examples, things like taking statins for high cholesterol — as far as I’m aware, taking a placebo statin has no effect on cholesterol levels. Or blood-sugar levels — we can’t influence that with our minds.

But one area where we do see kind of these dramatic and immediate effects is in the subjective symptoms that we experience, like pain, fatigue, nausea, depression. And there are lots of conditions where these symptoms are a real problem for people, from arthritis to giving birth to multiple sclerosis to cancer. I think people have this idea of the way that symptoms such as pain work, that it’s about physical injury to the body. And that is important, but our experience of that injury is created and controlled by the brain.

So if we feel stressed or under stress, then a kind of warning signal in the brain is amplified — and we feel that as pain, or nausea, or the other symptoms I’ve mentioned. But if we feel supported and cared for, the brain kind of feels like the crisis is over, and there isn’t much need, then, for the warning signals. And so it eases off on our symptoms. So that’s explaining a little bit about why placebos work so well in these conditions. Because taking a placebo — something you think is an effective medical treatment — it’s telling the brain that the crisis is over; there is no longer so much need for that warning signal that it was creating.

But there are other examples where a placebo can affect some of the more physical progression of the symptoms. Immune response is one — so, things like allergies and autoimmune disease. Our conscious expectation — just thinking we’ve taken the drug — doesn’t actually affect immune response. But there is another pathway called biological conditioning, which is where we learn an association between a drug and a physical effect. And this does influence immune responses.

For example, if you take a drug that suppresses the immune system a few times, your body learns the association between that drug and the suppressed immune response. And if you continue to take a placebo pill, your body automatically responds with that same suppressed immune-system response. And that happens automatically — it doesn’t matter what you believe about the drug that you’re taking.

So that suggests, potentially, that you could treat patients by alternating a placebo with real drugs?
Right, and this could help reduce drug dependence, in everyone from organ-transplant patients to those with autoimmune disease. And that will be very important for reducing side effects of toxicity of the drugs in these patients, as well as the cost.

But the thing about integrating that into medical practice is, isn’t that essentially fooling patients? How do you navigate the ethics there?
That’s always the obstacle with using a placebo — the idea that you’re fooling patients if they think they’re receiving a real drug. But there’s interesting research very recently suggesting that actually there are lots of ways we can harness placebo responses, without having to fool anyone.

There are trials now suggesting when you take a placebo, and you know it’s a placebo, that it can still work. It doesn’t necessarily work as well as a real drug, but it can provide significant benefits. There are trials in irritable bowel syndrome, depression, and ADD showing that.

And that’s possibly because the act of taking the medication makes people feel safe and supported, and like their condition is going to improve. Every drug you take, the benefit that you’re going to get from that is partly down to the direct effect of that drug, and partly down to the placebo effect. And some cases like I mentioned — statins for cholesterol, or chemotherapy for cancer — that’s going to be mostly, or all, a direct chemical effect. The placebo effect is going to be quite small. But then there are symptoms such as pain, or depression, where the placebo responses are very large. So in those cases, understanding how to maximize placebo responses is going to help patients respond better to the real drugs that they take.

And about the conditioning I mentioned — the idea of alternating drugs with placebos. That learned association is an automatic thing. It’s similar to, if you imagine biting into a lemon, and you start feeling the tingling in the salivary glands at the back of the mouth. It’s an automatic thing that happens. It doesn’t matter if you’ve got no intention of actually biting into a lemon — it just happens.

It’s the same as the response to immunosuppressive drugs. You can know perfectly well it’s a placebo — and in all the trials that are being done, people know perfectly well that’s what’s happening. So you get around the ethical issues in that way. It’s just a way of getting those benefits, but with a lower dose of the actual drug. And most patients are completely onboard with that, because they want their drug dependency to be reduced.

And what these studies are finding is that the experience that you’re receiving after taking a placebo — you’re not being fooled. Those are real, biological changes underlying those differences in your symptoms. It’s not all in your imagination.