The brain: can you really think yourself healthy? © Eiko Ojala

The brain: can you really think yourself healthy?

New research is discovering that the way you think about life can fend off infection, help you live longer and even spare you from the surgeon’s knife.

Nobody likes catching a cold. But it seems that we all have a pretty effective weapon that can reduce our chances of getting one – being happy.

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In a study published back in 2003, over 300 volunteers in the US were knowingly infected with a virus responsible for the common cold. They were then monitored for symptoms over the next five days. The results were clear. Those with the most positive outlooks on life were three times less likely to develop cold symptoms than those who were the least happy. Other studies have reached similar conclusions.

A positive mental attitude can have long-term health benefits too. In the US, the autobiographies of 180 Catholic nuns in their 20s and 30s were analysed by psychologists to see what they revealed about their personalities. It showed that those who were positive and happy tended to live 7 to 10 years longer than those who weren’t.

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In spite of such studies, the influence of our mind over our health has left some members of the medical community decidedly sceptical. But there’s a growing body of research showing that what goes on in our heads has a direct influence over how healthy we are. Not only that, our thoughts can even help cure us of some ailments. Importantly, researchers are now starting to understand more about the mechanisms at work – how our thoughts are connected to our physical health.

Stay positive

A researcher at the forefront of this field is Dr Laura Kubzansky, co-director of the Center for Health and Happiness at Harvard School of Public Health. One of her most recent studies – so recent, in fact, that it has not yet been published – involves just over 70,000 nurses in the US. In the research, she discovered that those who are the most optimistic have roughly 15 per cent longer lifespans than those who are the least optimistic.

In part, it is thought that differences in longevity like this are down to the fact that those with positive attitudes tend to do more exercise and smoke less. But it is not just that.

“People with higher levels of positive emotions do a better job of managing stress,” explains Kubzansky. “So a lot of the stress-activated biochemical processes, like higher levels of cortisol that are circulating and driving inflammation, are less likely to occur.”

Reduced stress also reduces ‘allostatic load’ – a medical term for the general wear and tear on the body, such as strain on the internal organs, that takes place under long-term stress.

The steroid cortisol gradually builds up and disrupts your brain from recalling memories while you sleep (© Getty)
The hormone cortisol is released in response to stress. High levels over long periods of time have a negative effect on health © Getty Images

But, says Kubzansky, this is likely to just be part of the picture – there will be other biochemical processes within our cells that are influenced by our positivity that we’re not aware of yet.

Part of the problem is that medical research has been understandably focused on getting to grips with what’s going on in our bodies when we’re ill, rather than when we’re feeling well and things are going right. “We’re not very good at looking at the biology of good functioning, we mostly just look at the biology of normal or bad,” she says. “But the time for positive biology has come.”

One of Kubzansky’s priorities now is to look at how our microbiome – the bacteria and other microorganisms that live inside our bodies, particularly in the gut – are influenced by how positive we are.

“There is some preliminary research that links depression to alterations in the gut microbiome, so it’s logical to speculate that you might get effects in the other direction,” says Kubzansky. The effect of our mental state on the microbes inside us is a big deal because the health and make-up of these microbes has been linked to several aspects of our physical health, such as whether or not we’re overweight.

Tricking the telomeres

There’s already evidence that the way we think can influence our DNA. For more than a decade now, the laboratory of molecular biologist Dr Elizabeth Blackburn at University of California, San Francisco, has been investigating the influence of our state of mind on our telomeres – the chunks of DNA that act as protective caps at the end of chromosomes.

Telomeres get shorter each time a cell divides and if they get too short, the cells in which they are located no longer divide and so they die. Short telomeres have been associated with everything from heart disease to lung conditions.

Protective telomeres (yellow) can be seen on the ends of this chromosome (blue) © Getty Images
Protective telomeres (yellow) can be seen on the ends of this chromosome (blue) © Getty Images

Blackburn was awarded the Nobel Prize in 2009 for her research on telomeres and telomerase, which is an enzyme that fights against the tendency of telomeres to get shorter and shorter over time.

Blackburn’s lab first looked at the telomeres of mothers who were caring for children with long-term health conditions. They found that the longer the mother had been looking after the child – so under stress – the shorter her telomeres. “It was very striking,” says Blackburn.

After that, they investigated other potential influences of the mind on DNA. It turns out that, on average, pessimists have shorter telomeres than optimists.

And being cynical isn’t good for your long-term health either. In one study on more than 400 British civil servants, they found that those who showed higher levels of ‘cynical hostility’ towards others – so were more likely to answer ‘yes’ to the question ‘most people make friends because friends are likely to be useful to them’ – had shorter telomeres.

Nobel Prize-winner Dr Elizabeth Blackburn researches telomeres and how they affect ageing
Nobel Prize-winner Dr Elizabeth Blackburn researches telomeres and how they affect ageing

But how can the way we think affect our DNA? For starters, when we’re stressed over long periods of time, levels of the hormone cortisol go up. “We know that higher cortisol dampens down the replenishing action of telomerase,” says Blackburn. The good news is that we can boost our telomerase levels.

In one study Blackburn was involved with, 30 volunteers spent three months at a retreat in Colorado meditating for six hours a day. By the end, levels of telomerase in their cells were one-third higher compared to another group who did not go on the retreat. It is thought that the telomerase boost wasn’t specifically down to meditation – it was more due to the increased sense of wellbeing the volunteers had. So anything that increases the sense of wellbeing is likely to have the same effect.

Placebo effect

When it comes to the influence of our minds on our bodies when we’re ill, the most widely known phenomenon is the placebo effect. Here, when someone takes medication that has no active ingredient, such as a sugar pill, it can do anything from numbing headaches to relieving symptoms of colds. It all comes down to believing the medication will help.

Examples of placebo treatments have been documented for centuries, but more recent research has provided some intriguing insights. For example, in one study in Italy, a placebo tranquiliser was better at soothing patients’ nerves before an operation if it was blue – or at least that was the case with female patients. Orange pills were most effective with the men.

The placebo effect plays a role when we have surgery too. Some common surgical techniques have been tested against ‘placebo surgery’, where a patient thinks they are having full-blown surgery but in fact they may just have an incision in their skin, or some other minor procedure.

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In many studies, the placebo surgery has been just as effective as the real thing. Research such as this is typically used to question whether certain surgical procedures should take place at all. But some scientists say that we’ve been thinking about the placebo effect in completely the wrong way. It’s not something to just test a surgical technique or a drug against, we should actually start to use it to treat patients.

“The placebo effect has been recognised for centuries – at worst it’s been viewed as a villain or a threat to medicine, such as when a new drug that developers have spent billions [developing] gets beaten by a ‘mere placebo’,” says Dr Alia Crum, principal investigator at Stanford University’s Mind and Body Lab. “But there is huge potential for it to be used for good.”

It’s a point Crum makes in a TED talk about the placebo effect (see below). She describes one of her experiments that showed a placebo cream with no active ingredients could be used to clear up allergic rashes, but only when the doctor was warm and friendly and showed signs that they were good at their job, such as wearing a badge saying ‘Fellow at the Stanford Allergy Center’.

“Our research shows that the placebo effect is alive and at play in every single medical encounter,” she tells Science Focus. According to Crum, we just need to train doctors to think about what they do and say in front of patients to harness the placebo effect more effectively.

In most placebo studies, each volunteer is told they will either receive the real treatment, or a placebo. But Dr Ted Kaptchuk, a placebo researcher at Harvard Medical School, decided to actually tell volunteers he was going to give them a placebo pill for irritable bowel syndrome. “Every placebo researcher in the world said ‘Ted, you are crazy’,” he says. But bizarrely, it still worked. The patients said their symptoms improved by 60 per cent. “In fact, it’s consistently worked in nine studies,” says Kaptchuk.

It undermines one of the common explanations of why a placebo works – that patients think they are getting the real treatment and so it works because they expect it to. Kaptchuk says that many of the patients who come to him for trials of these ‘open-label placebos’ have tried many other treatments for their condition that haven’t worked, and their hope and uncertainty seem to play a role.

Kaptchuk also says placebos tend to be most successful with conditions that have a big psychosocial component, where mental factors and perceptions are involved, such as chronic pain. “Open-label placebo doesn’t get rid of malaria, doesn’t lower cholesterol,” he says.

While we still don’t quite understand the psychology driving the placebo effect, there’s no doubt that it has an influence on the body. In research on placebo painkillers, for example, when neurotransmitters such as endorphins and dopamine are blocked, the placebo effect is stopped.

Power of the mind

The healing power of the mind doesn’t stop at the placebo effect. In his famous experiment, Russian physiologist Ivan Pavlov conditioned dogs to salivate when they heard a sound, such as the ticking of a metronome, if they first heard that sound several times when being fed. Similar ‘training’ could be used on patients too.

Studies have shown that when a medical treatment is paired with something else, such as a sweet or a smell, that something else can produce the same effect as the medicine after a while. In one study in Germany, for example, this technique enabled volunteers’ bodies to produce natural killer cells – cells that are part of the immune system – in response to a sherbet sweet. The idea is that in the future, the bodies of patients could be trained to subdue pain, fight infections or calm allergies by conditioning. Eventually, long-term medication may not be needed.

All of this research points towards a future where our minds play more of a role in our health, both when we’re well and when we’re sick. But there’s a million dollar question – how much can we actually change our mindset anyway?

“It’s not easily modifiable,” says Kubzansky. “I don’t think somebody one day says, ‘I’m going to be more optimistic today’. If it was that easy we’d all be in utopia. But I do think it’s modifiable with some focused attention.”

When it comes to harnessing the power of the mind in medical treatments, it seems there’s still work to be done to change the mindsets of some in the medical community. “The question is, how do you move the system?” says Kaptchuk. “Sometimes it’s science, sometimes it’s will, sometimes it’s the imagination.”

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  • This article was first published on BBC Science Focus in March 2019 – subscribe here

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