Jo Marchant, author of Cure, explains why the mind’s ability to heal the body is now being taken seriously by scientists who question alternative medicine

All in the mind? How research is proving the true healing power of the placebo

Why did you write this book?

We know that our thoughts and perceptions affect our physiology – in situations from stress to sexual arousal – but when it comes to whether these changes influence health, the question suddenly becomes much more controversial. You get claims of miracle cures at one extreme, while some sceptics argue that any role for the mind is deluded. I wanted to investigate the scientific research in this area to find out what the truth is.

Why is there so much resistance in the scientific community to the idea that the mind could have a role in healing?

Part of it is an understandable reaction to those exaggerated claims of cures. Sceptics may fear that allowing any role for the mind will encourage people to believe in the pseudoscientific ideas of alternative therapists. But there’s more to it than that. Ever since Descartes, scientists have viewed physical, measurable matter as more “real”, a more suitable topic for scientific enquiry, than subjective emotions and beliefs. I think that has led to an ingrained bias that because our thoughts aren’t “real”, they can’t influence the physical body. This makes no sense from a neuroscience perspective – where you can’t have a thought without a concurrent physical change in the neurons of the brain – but it causes a kneejerk reaction against the idea that our mental state might affect our health.

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Is there also a problem with how drug trials are designed?

A trial that tests a new treatment against a placebo is perfect for testing the direct biochemical action of a drug. But it can’t assess other elements of care, such as social support or stress reduction and positive expectation, because they are present in the placebo group too. There are studies suggesting that these components matter: patients with irritable bowel syndrome have greater relief from their symptoms when their practitioner is empathic rather than cold; patients with acid reflux disease do dramatically better after a 42-minute consultation compared to an 18-minute one. We need to take an evidence-based approach to studying these social and psychological aspects of care, just as we do when testing how drugs work.

Why do people believe in treatments based on evidence-free theories of the body?

Often, they believe they have personally benefited from alternative treatments such as homeopathy or reiki or acupuncture. When scientists then insist these treatments don’t work, these patients may be pushed towards the pseudoscientific explanations of their therapists. But there is a scientific explanation: factors such as social support and positive expectation inherent in these treatments can trigger physiological changes that ease symptoms.

What is the mechanism for how the mind influences health?

There are lots of mechanisms. Our mental state can be crucial in determining our experience of symptoms such as pain, nausea, fatigue and depression. Taking a placebo painkiller causes the release of pain-relieving endorphins in the brain, for example, whereas fake oxygen can reduce levels of neurotransmitters called prostaglandins, which dilate blood vessels and cause many of the symptoms of altitude sickness. When you experience a placebo response, it’s not imaginary or “all in the mind”: your symptoms are eased by physical changes just like those triggered by drugs. This is because warning signals such as pain are ultimately controlled by the brain. Feeling stressed, alone or under threat causes the brain to amplify the warning, whereas feeling safe or optimistic once a crisis is over triggers the brain to ease off. The experience of receiving medical care – whether real or fake – seems to reduce our symptoms for the same reason.

We need to take an evidence-based approach to studying these social and psychological aspects of care Jo Marchant

The mind can also affect physiological functions such as digestion, circulation and the immune system, and again there’s nothing mysterious or magical about this. All of these processes are controlled by the brain, via the autonomic nervous system. Feeling stressed or afraid can cause your heart to race and your bowels to empty, for example, and triggers an immune response called inflammation. These processes aren’t usually under conscious control - we can’t will changes to occur - but there are indirect methods we can use to influence them. Reducing stress is an obvious example.

What has been the response to the book. Have you fallen foul of both the alternative health practitioners and the evidence fundamentalists?

I was nervous about how it would be received but I’ve had positive reactions from everyone from neurosurgeons to reiki practitioners. A reviewer on the Science-Based Medicine blog described the book as “fascinating”, adding that it “challenged me to think more deeply about placebos, alternative medicine, and patient comfort”. This topic can be very very polarising but the responses have encouraged me that it is possible to have a rational debate about it after all.

Which was the story or treatment that surprised you the most, ie you went in a sceptic and came out a convert?

I met a transplant patient who drank green, lavender-flavoured milk to suppress immune rejection of his donated kidney. That sounds crazy, but it was part of a trial investigating how we can train our immune systems to respond to sensory cues such as taste or smell. This works through classical conditioning, where we learn to associate a psychological cue with a physiological response (such as when Pavlov’s dogs learned to salivate in response to the sound of a buzzer). Similarly, if you take several doses of a drug that suppresses the immune system, subsequently taking a placebo triggers an identical response, even though it contains no active drug – and regardless of whether you know it’s a placebo. In this trial, researchers used the distinctive green drink to strengthen the learned association and maximise the response. They hope reducing drug doses with placebos in this way could cut side effects for patients with organ transplants, autoimmune disease and cancer

Are some of these treatments just being ignored because they can’t be commodified by pharma companies?

Yes. I heard this over and over again from the researchers I interviewed. The majority of clinical trials are funded by pharma companies, which contributes to a medical system that prioritises the prescription of drugs, even for conditions such as pain that are strongly influenced by social and psychological factors. This serves commercial interests but doesn’t necessarily lead to the best outcomes for patients.

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Is there a particular treatment you cover in the book that you think deserves serious consideration as a mainstream treatment?

Using learned associations to reduce drug doses, as I’ve described above. Conditioning doesn’t just influence immune responses, it also works for pain, gut function, hormone levels, psychiatric conditions and even Parkinson’s disease. Understanding these processes better and working out when we can (and can’t) substitute drugs for placebos, with the same clinical benefit, could reduce problems such as drug toxicity and tolerance, as well as saving billions in drug costs. But there’s very little funding for the research – as you can imagine, drug companies aren’t exactly lining up to champion this approach.

During one chapter you knowingly take a placebo pill for a headache and you say it eased the pain. Have you restocked and put some sugar pills in your medicine cabinet?

My individual case doesn’t prove anything; my headache might have been short-lived anyway. But trials in conditions from migraine to depression show that “honest” placebos can still work (although not probably as well as placebos we think are real). I haven’t switched my pills for placebos though. I think it will be more helpful to maximise placebo responses associated with real treatments, so we can benefit from both their biochemical and psychological effects.

Do you feel like you’ve spent the past couple of years in the twilight zone of healthcare?

I feel like I’ve been immersed in a dramatically different perspective on healthcare, that in the future will become a routine component of conventional medicine. At least, I hope it will.