Instant Genius - How the mind affects physical health and vice versa

Episode Date: April 7, 2024

For years researchers around the world have viewed the brain and body as separate entities, to be treated using different methods and even in different hospitals. However, recent discoveries have turned this picture on its head. We now know that our brains and immune systems are intimately linked and have a huge influence on each other. In this episode I speak to Dr Monty Lyman a medical doctor, researcher and author who studies the relationship between the mind and the immune system. We talk about the latest science he outlines in his book The Immune Mind: The New Science of Health. Learn more about your ad choices. Visit podcastchoices.com/adchoices

This podcast is sponsored by name, audio and focal. Streaming has made music more accessible than ever, but true listening is about more than ease. It's about quality. British audio experts name audio, alongside French acoustic specialist focal, combine handcrafted tradition with cutting-edge innovation and high-end materials,

delivering digital precision with analogue warmth. So you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com. to learn more. Hello and welcome to Instant Genius, a bite-sized masterclass in podcast form. I'm Jason Goodyear, commissioning editor at BBC Science Focus. For years, researchers around the world have viewed the brain and body as separate entities

to be treated using different methods and even in different hospitals. However, recent discoveries have turned this picture on its head. We now know that our brains and immune systems are intimately linked and have a huge influence on each other. In this this episode, I speak to Dr. Monty Lyman, a medical doctor, researcher, an author who studies the relationship between the mind and the immune system. We talk about the latest science he outlies in his book, The Immune Mind, the new science of health. So first off, welcome to the show. Thanks having me on. So today we're talking about a field known as immunosychiatry. So personally, that's a new one on me. What exactly does it mean? That's a good question. It's a

It's a new word for a new field that, as his name suggests, explores the awkward space between the immune system and mental health. And I say it's an awkward space because it's a space that hasn't really been explored throughout most of medical history. And that's, there are various reasons behind that. It's, we haven't necessarily had the technology to explore a lot of it. But also, conceptually, it was just long assumed that the mind and the immune system didn't really have very much to do with each other.

So it's quite a new field. So how did you first become interested in it? So I have always been interested in the immune system, immunology, and I found it really interesting at medical school. I just love the idea that the immune system, it's sort of like a brain in the body you have this, this microscopic army of different cells, communicating to each other over long distances,

responding to different things that are entering the body, whether it's food or different kinds of microbes, and having some kind of memory as well. So they have a sort of network communication and a memory. And I was always fascinated that all of my medical school textbooks on the immune system said nothing about mental health and all the psychiatry, psychology textbooks said nothing about the immune system. And as I started to practice medicine as a junior doctor, a lot of really interesting research spanning these two fields began to sort of come to fruition.

And that's how that's sort of one of the reasons why. I became interested in the field. Eventually, moving to psychiatry from, so I initially wanted to do an immunology-based specialty, but now I'm now specialising in psychiatry, I sort of switched. As you've alluded to there, it used to be that the brain and body were considered as entirely separate entities,

something called dualism. Over recent years, it's become clear that this isn't the case. And things get even subtler when we include the immune system in this picture. So can you explain a sort of Cliff's Notes version of how that works and what the current thinking is? Yeah, it can get complicated because I think the immune system and the brain are two of the most complex things in biology. But the general thinking was for most medical science history that, so the immune system is a defensive system, a primarily defensive system against microscopic threats, bacteria, viruses, whatever.

and when it came to defence, the brain was more focused on the big threats that you could see or hear with your sort of classical senses. And it was sort of there wasn't really a need for them to interact. And that was sort of backed up by the fact that they, so most organs have sort of immune-related vessels. It's sort of like blood vessels, but they're called limp vessels. And it seemed that there weren't any limp vessels in the brain. And it didn't seem that there were any immune cells in the brain. You get immune cells and almost all other organs, but not the brain. brain. However, in the last 10, 15 years, we now know that, well, a lot of the cells in the brain,

so these are called glial cells. Glia is lots of an old word for glue. Basically, these, they were thought to be structural cells in the brain. Actually, they're immune cells in the brain. And in 20, as recently as 2014, we began to discover that actually there is immune anatomy surrounding the brain and connecting the brain to the immune system. There are limp vessels that surround the brain and there are immune cells that sort of patrol the substances coming out of the brain. So we now sort of have an anatomical,

a cellular model for why the brain and the immune system can link together. And then we also see stuff in the clinical world. So we've long known that when you have an infection, a lot of the symptoms that you have are mental. And then there's the flip side of that, which is psychological stress. And there's people have long known

that psychological stress is associated with changes in the body, but also sort of immunity in responses to infections and things like that. But now we're really understanding, beginning to understand why and how psychological stress can activate and change the immune system. So it's a really exciting time. We're really at the sort of the start of understanding this, the science, and there's a lot of hope for clinical treatments in the coming years and decades. So another sort of third key system that you mentioned is something called, the microbiome. So this is gaining even more popularity than ever now as a concept. But for those who don't know, you know, what exactly is it? Yeah, so the microbiome is the population, well, the community

really of microorganisms that live in and on us. These are mainly bacteria, but also viruses and various other types of microorganisms, most of whom are good for us, or at least they're not bad for us, but they're good in that their very presence keeps the bad bacteria, the bad viruses out. And there was a lot of, and there is a lot of excitement about the microbiome. It was thought that there was sort of more microbial cells in and on us than there are human cells. I mean, the latest of estimates are about, it's about equal, but that's still remarkable

so that we have as many microbial cells in and on us than we have human cells and far more genetic material on us and in us comes from microbes. and we're only just beginning to begin to understand what role these organisms play. But key ones, I mean, I focus a lot in the gut because a huge amount of, I mean, most of the human microbiome is based in the gut. And also most of the human immune system is focused on the gut, because actually that is the largest and most active external surface of the body, if you think about it, if you think about the gastrointestinal system as basically a hollow tube.

So the interactions between the microbiome and the immune system are hugely important, and we're beginning to understand that microbes can play very positive roles in physical, but also mental health. So that's it's another. I sort of try and think about seeing the human organism as a sort of community of mind and body and microbe, mind-body and environment. So the three are kind of inextribly linked. Yeah, precisely.

So let's have a look at how some of those links might manifest then. So you mentioned things like stress when somebody feels stress. So what's happening in their body then? How are these systems communicating? And that's a great question and a huge question. And we are beginning to see, first with some animal model studies, that stress is associated with changes in the body's immune system. I mean, there are various long-term human studies that show that,

chronic stress is associated with chronic inflammation and changes in immunity and also some changes in the microbiome. People understandably say it's quite hard, it can be hard to interpret those studies because if you're very stressed, you might also be eating poor diet and things like that. But we're actually seeing interesting elucidations of causality via mouth models, for example. So we now know that when some mice are stressed in an acute setting, various antibacterial bacteria are recruited into the bloodstream to go to the surfaces of the mouse dose of the skin, for example. And this sort of mirrors what we know from human studies when humans are psychologically stressed, so when they're made to answer hard sort of arithmetic problems

in front of a sort of a cross-looking panel of very, very serious-looking people. A lot of their immune markers go up. And the thinking from a sort of an adaptive point of view is that if your brain notices a threat to your body. It notices a lion in the middle distance. It is adaptive, and for our ancestors that were more likely to survive, might have been those who were able to prepare for a potential breach in the skin's defenses. The idea is the activation of the mind, the phytokyto-fight response, we think about that in terms of adrenaline and the nervous system,

but actually, if that can recruit the immune system to be activated, then that could have a beneficial role. And that might actually suggest why when people are psychologically stressed, they're more susceptible to viruses, so things like colds, because there's a sort of a temporary immune skewing towards antibacterial because most of the things that will sort of break the skin through a lion's tooth or enemy spear

is more likely to be bacterial. That's probably the most important, more important thing in the short term. So a lot of the research into stress and the immune system and it's sort of focusing in on these things. I think it's important to say that, well, firstly, this is sort of an activation not, of a unified defence system. So the body is not designed to have lots of nice, different organ systems to help doctors choose their medical specialties.

You know, they are interlinked to serve various purposes, one of a huge one of which is survival. And it makes sense that the immune system and the brain, the mind, would recruit each other for the joint purpose of survival. So I use a phrase, the defence system, which is used by some researchers in this area to sort of conceptually think about those things together. But I think just an important caveat is that stress is adaptive

and important and useful, as is inflammation, activation of the immune system to fight off bacteria and pathogenic bacteria and viruses and initiate healing processes. It's very important. the problems come when that becomes chronic. So chronic stress and chronic infections can do similar things to the body and can accelerate many of the diseases of the modern world. Another topic that you discuss in the book about how this feedback loop system works is regarding dementia. So I found that

particularly surprising. Yes, that's a really interesting area. Dementia is huge, in very different way, in sort of every way you can think of in terms of the number of people being affected. All of us are touched by the effects of dementia in some way and the devastating it has on the individual level as well as the society level. And the fact that we just don't have any effective treatments for it really. I mean, in specific cases, there are some things that show small amounts of evidence. But what's really interesting is that there is lots of different elements of research that is sort triangulating to suggest that in, you know, some people at least, chronic inflammation is associated with an increased risk of developing

dementia. So dementia is lots of different conditions. So Alzheimer's is the most common type of dementia. We've known for a long time that Alzheimer's is associated with these buildup of proteins in the brain, called amyloid beta plaques and tau tangles. And we're now, I mean, we've now developed quite a few treatments that can reduce those tangles, but there's no significant evidence yet, I hope that one day one of these will be a cure. None of these significantly really make a huge amount of difference. But there is some evidence that these protein buildups may be related to, they may be the consequence of inflammation in the brain. The idea that chronic inflammation might, it's not necessarily direct infection of the brain, but chronic inflammation

of the body that begins to infect the brain and affects some of the immune cells in the brain. The sort of the collateral damage of that may, one of the endpoints of that might be dementia, and therefore, immune-focused treatments, perhaps quite early on in the disease process, you know, may be an avenue for research. That's a potentially really interesting area. And for other types of dementia, say vascular dementia, the second is common cause. There's a huge amount of evidence now that atherosclerosis, which is basically the clogging up of arteries, which can cause heart attacks, it can cause strokes,

which can lead to small strokes lead to vascoate dementia, as well as vascular disease in your legs, various different things like that. It was initially thought that it was just sort of buildups of fat, and it's not quite as simple as that. It's actually chronic inflammation at these conditions. And the idea that, you know, this sort of this collateral damage from multiple microbial wars

manifests itself in these diseases of the modern age, which are obviously increased by age. So if you live longer, you're more likely to get dementia, because you're probably more likely to experience these things, but maybe there are other different lifestyle factors that can contribute to that. So it's a complicated area, but it's understanding the immune system is going to be really exciting. It's really exciting for future treatments.

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Yeah, so another topic that you discussed, which I found particularly interesting, was the idea of loneliness and the damaging effect that can have on us. So what do we know about that at the moment? I find this really interesting because exploring the effects of the immune system on the mind and vice versa, there are lots of subjects which, as medical students that, I think it's taught differently these days, but subjects that were taught as quite sort of woolly or soft or irrelevant are actually biological as well. So loneliness, for example, you know, we can think about loneliness is, you know, obviously that's sad,

but does it really matter medically? well, the answer is yes, the body, if you think about it from a survival point of view, the body sees isolation, whether physical isolation, social isolation, rejection, various types of oppression, it sees those things as threats to survival. And that can contribute to inflammation and it can mark itself on the body. And there is, there's an emerging literature looking at that, which is really interesting. And it seems that areas of the brain actually, so there's an area, I'm particularly interesting called the insular cortex. But the brain,

and this is a bit of a generalisation with the brain, seems to process various threats, the sort of physical pain, but also social rejection and even inflammation, sort of processes them in a similar way. They're seen as sort of threats to the body, and they can initiate stress responses and inflammation in and of itself.

So actually, I think, tackling things like loneliness and systemic oppression, they're not just sort of social interventions, they are public health interventions and they directly can directly relate to physical health outcomes as well. It's just it's been, because there are lots of causes and effects, it can be quite hard to measure, but actually we're beginning to sort of tease this apart. So we've talked about the three different aspects of this system then. So let's have a look, what we can do to keep it healthy. And I know you're quite keen that you don't want to give out sort of health hacks or that sort of thing in the book. But you do mention three areas which we can concentrate on to perhaps

allow ourselves to flourish a little bit more. And it's eat, play and love. So let's go through those in turn. So let's have a look at each. What role does diet play in all of this? We've mentioned the microbiome. Yeah, I think, yeah, you've sort of articulated that very nice. nicely. I think the more practical element of the book is potentially, is probably the smallest part of it because I think there's a huge amount of really interesting evidence that we're getting. And some of it, we can sort of practically apply. But there's more, I think there's more to come. But I think there's quite a lot we can, we can think about now. So yeah, with eat, play love with eat, talking about the microbiome, you know, the microbiome, it plays

lots of roles in physical and mental health. And the easiest way of adjusting the microbiome is is through diet. I don't necessarily want to be prescriptive with dietary interventions. Some of the research I'm doing is looking at a very specific, a different type of diet with specific people with a certain condition. So I think there's no one diet fits all. But if you want to have a healthy microbiome, what is a healthy microbiome? We don't know what the perfect microbiome is, but all the evidence suggests that diversity forgets health. The more diverse your microbiome, you've got microbiome, the more likely that is to be linked to better health. How do you get a diverse gut microbiome or the evidence suggests that it is providing lots of different types of food for the microbes. One of their microbes's main

food is fiber. A lot of that you can get from different types of plant foods. So a diversity of plant fiber is good for feeding the good bacteria in your gut. And there is also some really interesting emerging evidence from some new studies suggesting that placing new types of of bacteria into the gut via fermented foods can also play a role. So I'm visualising this at the moment as sort of creating a medicinal garden in your gut. So you've got the fertilizer, which is the fiber, and you've got the seeds, which are the microbes, introduced in the microbes.

And I like the idea of gardening, because it encourages the idea of cultivation. You know, it's not, as you said, it's not like a health hack. It's something that you do slowly but surely, you know, you don't suddenly. empty the veg aisles in your supermarket because that would just make you feel miserable. It's sort of like if you're going to the gym or starting to just get out and go for runs or whatever. It's slowly introducing these

an increase in dietary fibre of different variety and having fun with that as well. And potentially introducing fermented foods that's something that I do myself. And there's interesting emerging evidence. But also seeing, you know, if you think about it, if you think about that you're cultivating a community of bacteria within you,

then eating is always communal. You're sort of loving yourself, but not in a kind of isolated, selfish way. It's sort of you are, you are tending to an ecosystem of community. We know all about the macro scale ecosystem when we think about the world, deforestation, pollution, climate change,

but actually the idea that sort of charity starts at home focusing on having a diversified microbiome and looking after, you know, thinking about that you are something bigger than yourself, you're a community. I think so psychologically and physically is really helpful. That's what I would suggest from the eating point of view. I mean, there's more to diet than just eating diversity of plant fibre,

but I think that's a good place to start. So that's where I'd mainly focus on with eat. So let's have a look at play then. What do you mean by that? Yeah, I initially thought about focusing a lot, focusing on exercise, but actually I think the word play is key. in a similar way to enjoying eating different kinds of foods and cultivating a diverse gut microbiome, you know, humans, all kinds of animals are adapted to play and explore the environment,

not just for physical health, but for mental health, you know, in terms of the brain wants to, and I won't go into detail about the kind of the predictive processing element of the brain, but that's a really interesting area of neuroscience. The brain wants to go out and test the environment to, to refine its model of the world. Going out and exploring the environment, if that can be combined with exercise, then I think that's hugely important.

So looking at exercise, there's a new field of research showing that exercise is associated with reduced inflammation. So if you go for 10K run or you do lots of lifting lots of heavy weights, you're going to cause inflammation in the short term, but actually over a longer period of time, the body, the immune system begins to adapt.

And actually it reduces chronic inflammation, whatever type of exercise. And there's some really interesting, very detailed studies looking at specific cells that respond to movement in bones that when they're activated, they produce good immune cells, basically. So if you'd look at all of the joints in our body, you can see that we were made to move. The human baseline is regular movement with rest as well and good sleep, of course. so basically movement is good for the immune system for mental health for physical health I think playful and purposeful movement are key it has to you know it's got to be something that there's either something that you enjoy or that fits into your story if that makes sense so I think seeing exercise as an element of cultivation is really important so along with play comes rest as well

and there is also, this is a very emerging field, but there's some scary evidence to show that if you have, you know, long periods of sleep deprivation, it can sort of rapidly reduce the number of immune cells, specific types of immune cells called natural killer cells in your blood, which is not good in the long term. It can be a slight depressing reading when I'm, you know, I myself have a happy young child and I'm not getting as much sleep.

That's why I think focusing on these circular systems with the mind in the body and the microbiome intertwined is key because it's not like a checklist of all these health hacks that you need to do otherwise your health has got a full part it's actually working out what are the things that you can change to improve your microbiome physical health mental health and if it's if for a period of your life you know sleep isn't going to be as good then actually focusing on the connection and community and love is actually an intervention in and of itself so that moves from sort of feet to play to love. And I was initially going to call this chapter to think about, you know, psychological,

mental health ways of sort of reducing stress and looking after your immune system. Actually, I think love is a better word in many senses. So, you know, I've alluded to the fact that, you know, well, the human body, roughly speaking, is sort of in terms of size-wise, is sort of halfway between the size of the earth and the size of the smallest microbes. So, you know, we often think about loving our environment, our loving, loving, loving the world and biodiversity, but actually loving inwardly in that sense, in that sort of communal sense is, I think, is really, really important. Focusing on your mental health is a physical

health intervention as well. I think one of the reasons I wrote the book actually is because there's no mental health condition that is not so physical, and there's no physical health condition that doesn't have a mental health aspect to it. And often when we think, you know, if we're suggested, if we're a chronic condition and there's any suggestion of any psychological help that you can get or anything that you can do to improve your mental health or stress. There's a way that medicine has developed in the West in particular. This is implicit suggestion that it means that it's all in your head or, you know, it's something to do with your personality that you know, but that can be further from the truth.

You need to tackle any condition from a physical and mental health point of view. focus on various things to try and help with, basically focusing on reducing stress, mindfulness and various other things. But I think with that, that's the area I definitely want to be, you know, less prescriptive in because everyone's very unique.

But focusing on these things that might seem a bit, yeah, a bit wully, things like gratitude practice and mindfulness or meditation or various different things like that or journaling, you know, actually if you can focus on something that can help reduce stress and improve mental health, and that is also a physical health intervention. And Robert Sopolsky, who's a well-known stress researcher in the US,

does a sort of a 20-80 rule with stress and says, I mean, it's as easy said than done, but often 80% of the stress can be reduced with 20% of the effort, and it's basically realizing that chronic stress is damaging to physical health. and if possible it is being able to ruthlessly try and work out how to cut that out in your life but yeah so those

those are some of the more practical ways in which we can try and sort of nurture a combined system of mind body and mind body and microbe so I think there are things that can be specific for specific people but I think

what I like about I think what I would encourage people to think about reading the book is is focusing on understanding how these systems work and how we have a combined defence system. And actually, I believe that very understanding that the mind and the body, the immune system and mental health are intricately linked,

that understanding, I think, will then speak into whatever personal situation you're in and should inform physical health, should inform more practical health interventions, if that makes sense. because I think in our society, we're often split into the minds or the bodies when it comes to health conditions. It's either physical health condition or a mental health condition, but actually understanding that the science behind why they're interlinked

and the sort of the logic behind why they're so connected isn't just interesting. It will change the way you see yourself and your health. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. to Monty Lyman. To discover more about the topics we've just discussed, check out his book, The Immune Mind, the new science of health. If you liked what you just heard, please consider subscribing to Instant Genius on your preferred podcast platform. The current issue of BBC's Science Focus magazine is out now. Pick up a copy wherever you buy your favourite magazines or download a copy on your app store of choice. You can also find us online at sciencefocus.com. This

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