For centuries, philosophers and scientists have debated the connection between mind and body. French philosopher René Descartes famously proposed in the 1600s that the two were divided and separate, made of different stuff. How could something as ephemeral and subjective as individual consciousness be produced by the physical hardware of the body, he and others wondered, a question that continues to beleaguer scientists who study consciousness today.

After World War II, the rise of placebo science offered some hints. Researchers have increasingly come to understand that a person’s expectations, positive or negative, have a powerful influence on their health. Give a patient a sugar pill, with no active ingredients, and tell them it’s a cure for what ails them, and many people will start to improve. On the flip side, tell a patient that the therapy you’re about to deliver will give them a headache, and most of them will develop a headache, even if no real therapy was delivered at all.

Now a team of scientists from Israel have identified another form of thought that can powerfully shape how the body heals: voluntary attention. At first blush, their findings, published in Nature Communications, seem to run counter to conventional wisdom. The scientists gave a small group of participants a histamine skin prick to produce an inflammatory response and then asked some of them to pay close attention to the inflammation for about 20 minutes, and the rest to distract themselves. What they found is that the immune system functioned better when people paid close attention to the inflammation than when they found a diversion.

I spoke with neuroscientist and study author Liron Rozenkrantz, who researches the neurophysiology of conceptions, beliefs, and expectations at Bar-Ilan University, about what the findings tell us about pain, the placebo effect, and interoception, the internal sense that lets you feel, understand, and respond to signals from the inside the body.

Read more: “Take Two Sugar Pills and Call Me in the Morning”

Do your findings tell us anything about the placebo effect?

I come from placebo research. That’s where my journey began. The entire first 15 years of my career were focused on the placebo effect. I thought the placebo effect was the coolest and most important thing we could ever study. At its heart is a simple question: How can you change a person’s thoughts to improve things in the body?

But to me, the placebo effect is also a case study for something much broader: how our thoughts, expectations, or beliefs—our higher order cognitive processes—may be able to regulate physiological processes in our body at every single moment. Why are we constrained to this clinical setting where you give a sham drug or sham treatment and watch what happens, when higher cognition—what we think, expect and so on—could be just regulating brain-body communication on an every-minute basis?

That’s how I started up my lab and how the idea for this study came to be.

You specify in your study that it’s voluntary attention that matters here. Why does it have to be voluntary?

The point is to say that we can control it, which is different from the placebo effect. You cannot self-administer a placebo effect. There are studies beginning to try to tackle that aspect, but traditionally, a placebo effect is by definition a deception. You’re being led to believe or expect that something that contains no pharmacological ingredients would improve your own condition. You think you’re getting something real, but in fact it’s a sham. It changes neurobiological processes that respond to the expectation, but deception is a key ingredient. And in our study, deception plays no part. We simply told people to attend to the sensations from this inflammation that we created on their skin versus distracting their minds away.

We weren’t aiming to show the placebo effect doesn’t exist. The placebo effect inspires every single thing we do. But there’s this distinction between the two fields of study.

What about more recent open-label placebo studies, where people do know that they’re getting a sham and it still has a powerful effect?

That’s what I had in mind when I said we’re trying to find ways to tackle the self-administration challenge. We’re trying to find ways to use placebos in the clinic more ethically. I’m not fighting the power of the placebo, though. It’s great, and I’m in favor of studying it and making it more useful. But in my lab, we’re trying to understand the ways in which our higher order cognitive processes, our thoughts, expectations, and beliefs, influence physiological regulation on an everyday basis. It doesn’t have to be in a clinic. You don’t have to have a condition that needs to be improved. You’re just a normal, healthy person.

In our study, the participants were just encountering this very common immune challenge, which is neurogenic inflammation, an inflammatory response initiated by the nervous system rather than the immune system. We wanted to know whether attention versus distraction could contribute to how the body resolves or handles this kind of inflammation. Why would it? This kind of minor peripheral inflammation is something the body can handle very well on its own. But what we found is that actually, whether you’re paying attention to sensations from this inflamed site has a huge impact on your ability to regulate that inflammation.

Why has the baseline assumption been the opposite—that too much focus on an injury or illness can make it worse? Does this mostly come from placebo studies?

Exactly. That’s the difference. In placebo studies, you change what people expect. You either induce positive expectations or negative expectations about something that’s about to happen. We induced no expectations. We just told them, “Attend to whatever you feel, just be with it,” or we distracted them away. I do think that attention versus distraction toward these sensations could be an even more basic mechanism than expectation, which is what’s at work in the placebo effect, but I’m not sure about that because we haven’t studied it yet.

Are there reasons to believe that the effect you found is only applicable to something as small as an allergen or a prick, or is there evidence to suggest that it might have a greater range?

We only tested this one specific immune model, so we cannot generalize. We didn’t work with any people with chronic illness, chronic pain, inflammation, or clinical disorders. These people were all healthy participants. I cannot recommend that anyone stop taking painkillers. But our finding raises interesting questions and ideas about the purpose of pain and the fact that the most common, even intuitive, thing that we do when we’re in pain—it’s even a clinical practice—is to distract away from it. In cases where pain is excruciating, that probably makes sense. But we cannot induce excruciating pain in the lab, so I cannot speak to these cases.

What we do find is that signals from inflamed sites travel to the brain anyway, whether you attend to or distract away from the inflammation. But apparently, subjective experience needs to be more intense in order for the brain to be able to use it most efficiently. We already knew that paying attention to pain changes how the pain is represented in the brain, but apparently it also changes the brain’s ability to then regulate the downstream immune response. It regulates the response much more efficiently when you attend to the sensations.

It suggests that there are more ways to understand how what we think can change how the body responds to stuff. This is one way. We didn’t think about immune regulation as something that requires cognition. Host defense evolved before consciousness did.

Read more: “Sugar Pill Nation”

Do we know that for sure, that host defense evolved before consciousness did?

Some organisms consist of a single cell and can protect against attacks, so the immune system evolved before consciousness.

Do we know for sure that one-celled organisms don’t have consciousness?

I can’t speak to that, but it’s not intuitive to think that a cognitive contribution is necessary to regulate the immune response.

Does the growing science of interoception, the internal sense that lets you feel, understand, and respond to signals from the heart, the stomach, and other parts of the body, tell us anything about the link between attention and immune response?

I’m so glad you asked this question. I wanted to call this paper, “Interoceptive Attention.” Interoception is huge right now, and it can be interpreted in two ways. One is that interoception is the means by which the brain connects with other body organs and speaks with them. The second way to think of interoception is how you sense your body from the inside: Pain and itch and stuff like that are also interoceptive sensations.

For me, what that means is that interoception isn’t just about sensing and the brain-monitoring stuff. It’s also the feedback loop that’s activated, how the brain then regulates whatever is happening next. So it’s a loop of sensing, perceiving, and then regulating. It’s not enough to sense. What we find is that you need to also subjectively experience a signal in order to improve regulation.

Is there any research out there that suggests that taking pain medications can interfere with one’s powers of interoception?

We’re in favor of medicine, and whatever you need to feel better. But it’s a great question, and I don’t have the answer to it. When it comes to exteroception, our sensory powers to pick up everything that happens in the external world, it’s super clear that if you attend to a stimulus, then you process it better and you respond to it more efficiently. Why wouldn’t the same be true of interoceptive sensations? We need to think more about the equivalence between exteroception and interoception.

Lead image: CRCS / Adobe Stock