Mind Over Matter

The title of this post is the same as the title of a Feature article by David Robson in the 25 August 2018 issue of the New Scientist. The subtitle is: “You really can think yourself healthier and happier.” The article begins, “A positive mindset isn’t just mental—it can trigger physical changes making you fitter, slimmer, more energetic and less stressed. It will even help you live longer.”

Dr. Alia Crum told the global movers and shakers at this year’s World Economic Forum in Davos, Switzerland, “Our minds aren’t passive observers simply observing reality as it is; our minds actually change reality. The reality we experience tomorrow is partly the product of the mindsets we hold today.” Dr. Crum heads the Mind & Body lab at Stanford University.

When she read about the placebo effect as a psychology student she had the following eureka moment: if our expectations can influence the effectiveness of a drug, perhaps something similar can happen in other situations also.

In the course of her research she and her fellow researchers have discovered that our mindset affects everything from our weight and fitness to the physical toll of insomnia and stress, even how well we age. Two people could have identical genes and lifestyles, but one can end up healthier than the other, thanks solely to their different thoughts.

There have been many healthy memory blog posts on placebos, so readers should know that placebos are inert pills used in most clinical drug trials. Participants are randomly divided into two groups: half taking the drug being tested, the control group taking an identical looking sugar pill. With no active ingredient, the placebo shouldn’t have any effects. Yet it typically results in measurable changes triggering the release of natural painkillers and lowering blood pressure, for example—all due to people’s expectations. Patients can even show these benefits when they know they are taking a placebo. There is also a nocebo effect. Expectations of a pill can also produce side effects such as nausea and skin rashes.

Crum was surprised that relatively little has been done to understand and harness the facts to improve health and well-being. Governments spend large amounts of money encouraging us to adopt healthier lifestyles. Crum wondered what if our efforts could be boosted or undermined by the very psychological processes that influence a drug’s efficacy through placebo and nocebo effects. She has spent the past decade investigating this possibility.

In one of her first experiments she examined the fitness of 84 hotel cleaners. She suspected that few of them would be aware of the sheer amount of exercise their job entails, and that this might prevent them from gaining the full benefits of that workout. To manipulate their mindsets, she gave half of them detailed information about the physical demands of their work—that their work hoovering burns 200 calories an hour—and told them that their activity met the US surgeon general’s exercise recommendations. One month later, despite reporting no change to their diet or activity outside work, the cleaners who received the information had lost about a kilogram each, and their average blood pressure had dropped from elevated to normal. The others showed no difference. This was a small study and Crum didn’t record actual behavior. She concedes, “It could be that they were putting slightly more oomph into making the beds.”

A follow-up study with a colleague, Octavia Zahrt, bolstered the idea that people’s expectations directly influence their body’s response to exercise. That study used data from health surveys monitoring more than 60,000 people. Zahrt found that the “perceived fitness” of the participants—how they felt compared to the average person—was a better predictor of their risk of mortality than the amount of time they said they spent exercising. Some of them wore accelerometers for part of the survey period. Still, after taking their actual physical activity into account, the influence of how they perceived fitness remained. Overall, people who took a more pessimistic view of their fitness were up to 71% more likely to die during the survey, compared with those who thought they were more active than average—regardless of their exercise routine.

The brain can directly control blood pressure through the autonomic nervous system. Crum suspects that a poor perception of your fitness could be triggering inflammation and the release of hormones such as cortisol, which might help determine how the body responds to stress. Her team is investigating possible mechanisms but, she says, it’s not too early to take advantage of these effects. Cruz’s advice is not to deceive yourself about your fitness, but to make sure that you don’t undervalue the exercise you do, either. Also avoid comparing yourself critically with your peers particularly if they are exceptionally sporty.

Crum has also documented other ways in which our mindset could be harming our health. A nocebo effect could undermine efforts to lose weight by dieting. In 2011, Crum offered volunteers a milkshake at her lab, then measured their levels of the “hunger hormone” ghrelin, which normally drops after a meal. Although everyone received the same shake, some were told it was healthy while others were led to believe they were having an indulgent treat. Those who thought they had drunk a low-calorie shake showed markedly higher levels of ghrelin afterwards, which left them feeling less full.

Ghrelin doesn’t affect appetite alone. By signaling food deprivation, the hormone also slows down metabolism, tipping the body towards storing fat rather than burning it. It makes evolutionary sense to reduce energy consumption when resources are scarce, but it is bad news when we are trying to lose weight. Crum says, “When people think they are eating healthily, that is associated with the sense of deprivation. And that mindset matters in shaping our physiological response. Instead, she suggest, dieters should cultivate a “mindset of indulgence,” savoring the texture and flavors of whatever they are eating.

Non dieters could also fall prey to this effect. When drinking a sugary beverage the brain doesn’t seem to recognize the liquid as a source of energy, and fails to adjust digestion accordingly so that we tend to eat more afterwords than if we have eaten solid food containing the same number of calories. We can subvert this effect by changing our expectation. Richard Mattes at Purdue University primed people to believe that the energy drink would solidify once it reached their stomach. As well as lowering gherkin levels, this increased the insulating response after consumption, leaving them feeling fuller. That was followed by a decrease in the daily energy they consumed.

It should not be forgotten that mind over matter is also important for aging. As has been reported in previous healthymemory posts; people who view aging positively live 7.5 years longer than those who associate it with frailty and senility. Negative perceptions are not merely the result of poor health; they can foreshadow symptoms by as much as 38 years.

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