That Neuroscience Guy - How Loneliness Changes Your Brain

Episode Date: November 21, 2021

Everyone handles it differently, but we all feel lonely sometimes. What you may not know is that loneliness can have a severe negative impact on your brain. In today's episode of That Neuroscience Guy, we discuss what loneliness does to your brain. 

Hi, my name is Ola Kregolson, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. Loneliness is not fun. And we've all experienced it, especially with the ongoing COVID pandemic. Loneliness is that empty feeling when we literally feel like we're alone in the world. And surprisingly, we can even feel loneliness when other people are around. We don't actually have to be alone. We can be in a crowded room and still feel lonely. And we know loneliness is not good. Loneliness has been linked to increased incidence of depression, increased incidence of anxiety, alcoholism, and drug abuse. There's even emerging work that suggests loneliness can actually make you more prone to getting sick.

And even more recently, loneliness has been tied to the onset of dementia and Alzheimer's disease. On today's podcast, we're going to talk about the neuroscience of loneliness. So what's happening in the brain when we're lonely? First of all, it starts with hormones. But what are hormones actually? Basically, hormones are your body's chemical messengers. They travel in your bloodstream to tissues or organs, and they work slowly over time and they affect all sorts of things. For instance, hormones underlie growth and development. They underlie our metabolism, how our body gets energy from the foods we eat. They're tied to sectional function, those drives that we feel

occasionally. Hormones are a crucial part of reproduction. They even impact our mood. Now, where are hormones made? Well, the hormones are made in the endocrine glands that are basically a group of very special cells. And the major endocrine glands are the pituitary, pineal, thymus, thyroid, adrenal, and pancreas. And these are the parts of the body that produce these hormones. Now, while they're not specifically made in the brain, because a lot of these places aren't in the brain, they impact brain function. And of course, men produce hormones in their testes and women produce hormones in their ovaries as well. Those are those gender differences that we know all about. So how does loneliness actually make

you physically ill? And what's the role of hormones in this? Well, evidence has accrued that suggests that loneliness causes the release of hormones that suppress healthy immune system function. So in other words, loneliness, and when we're feeling lonely, we're releasing hormones that are literally dialing down the effectiveness of our immune system and our ability to fight illness. And that's how loneliness can make you actually sick. And these biochemical changes in hormones are not good. Not just the sick part, but they've been shown to accelerate the speed of cancer, hasten heart disease, and they're even related to the onset of dementia that I mentioned a few minutes ago.

to the onset of dementia that I mentioned a few minutes ago. So the release of these hormones has a massive impact on our body and our brains. Now, of course, there's more to loneliness than just hormones. Recently, a very large MRI study in the UK found several differences in the brains of lonely people. These differences were centered on something called the default mode network. We've talked about it before, but the default mode network is basically a set of brain regions involved in inner thoughts, such as reminiscing about the past, future planning, our imaginations, and even thinking about others. Now let's do a little bit of a dive on the default mode network, because I feel like I've brought it up on a couple of episodes but we haven't really really pulled it apart. The default mode network is a collection of brain regions. It's sometimes just called the

default network. Some people have called it the default state network and anatomically you would call it the medial frontal parietal network. But it's just a group of brain regions working together. And the key ones in the default mode network are the medial prefrontal cortex, the posterior cingulate cortex, the precuneus, and the angular gyrus. Now, what the default mode network is famous for is it's more active when we're not doing much. It was actually kind of discovered by accident. Researchers were looking at MRI data and fMRI data, and they weren't expecting to see the brain all of a sudden lighting up

because people were supposed to be just sitting quietly. But instead, they saw the activity in this network. When the default mode network spins up, what's going on? Well, basically, it's being associated with daydreaming and mind-wandering. So it's the parts of the brain that actually underlie those daydreams that we have or are filling our head with thoughts when we're mind-wandering. You can typically see it when people are thinking about themselves. So they're thinking inwardly. thinking about themselves. So they're thinking inwardly. You're remembering the past or you're planning the future. And also typically what you see is activity in the default mode network is

suppressed. So it goes away when people focus on specific tasks. So it's almost like this network needs to be shut off for us to be able to do some externally generated thing that we want to do. shut off for us to be able to do some externally generated thing that we want to do. Now, what's the role of the default mode network in loneliness? Well, researchers have found that the default networks of lonely people are more tightly wired together, and they've even found structural differences. There's a difference in the amount of gray matter volume in the brain that's present. of gray matter volume in the brain that's present. So the default mode networks are wired together more tightly, and there's even these differences in actual tissue. Researchers have also found differences in other parts of the brain, of course, but in lonely people, the default mode network, well, if you think about what we were talking about, it's tied to remembering the past and envisioning the future, thinking about a hypothetical present. So the fact that this

network is more active in lonely people is because they're probably more focused inwards, all right? As opposed to being out in the world and doing things, they're tied to those thoughts of the past, and that's why loneliness can also be tied to depression. So basically the idea is that in the absence of a social experience, lonely individuals are turning inwards. And that's why the default node network is more active, and that's why we see differences in that network in lonely people. So it's kind of weird, but people that are lonely, there's actually more brain activity, but it's in the default mode network. So we've got hormones playing a role. We talked about that at the outset, and we've gone through the default mode network and what

it might be doing when we're lonely, but there's more to it than that, of course. Another group of researchers that was doing a meta-analysis, so that's when you take a whole bunch of research studies and you look at what findings were in common, and they were looking at evoked responses. So they were showing people pleasant versus stressful image in social versus non-social context. So imagine an image of people having a dinner, that would be a social context and it would be pleasant. Or you might have a stressful image in a non-social context. So an image or a picture that makes you stressed and there's no other people in the picture,

so it's non-social. And when they did this, they found that the brains of lonely people were responding differently. In the brains of lonely people, they found differential activity in the prefrontal cortex, especially the medial prefrontal cortex and the dorsolateral prefrontal cortex, the anterior insula, the amygdala, the hippocampus, and the posterior superior temporal cortex. So why is the brain activity different? Well, it probably goes back to the hormones and the other things we've told about. People that are lonely have differences in their brain function, and it's because of these underlying changes like the differences in the default mode network and also

the release of hormones. Now, of course, there's individual differences in this. Some people handle loneliness better than others. That's just the way it is. I've found that a lot of people assume that our brains are all the same, but they're not. Just like the wide range of physical differences that we see, people have different heights, different weights, different hair colors, the color of their skin is different. Well, our brains are just like that as well.

Our brains are all different. There is an average brain. It's actually called the MNI brain for the Montreal Neurological Institute. And it's an MRI scan that you can find that's supposed to be the average brain, just like there is an average height and an average weight. But not all of us are average. And there's a wide range of people. So in other words, some of us are simply just better's a wide range of people so in other words some of us are simply just better hardwired for loneliness so in summing up where we're at now remember there's this difference in hormones and those hormones have an impact on on our bodies and the way we feel and function there's this difference in the default mode network there's more activity in

this and the people that are lonely and because because of these two changes, we also just see overall differences in brain function in people that are lonely. The different parts of their brain that are activated by images in the study I talked about, or just life in general, they're functioning a little bit differently because people are lonely. Now, what is the neuroscience answer for loneliness? Now, what is the neuroscience answer for loneliness? It's really simple. Interact with people. Social interaction is associated with all sorts of positive changes in mental health, and we see these changes in the brain. are over the age of 65 and the ones that stay at home by themselves have a lot of differences in brain activity and not good brain differences relative to people that stay more social. And this isn't just for those of us that are getting older, this is across the lifespan. When we interact with people out in the world, parts of the brain light up, our emotional centers

light up, the amygdala, which we've talked about a lot, and the insular cortex. And we also see activity in those reward systems. So the ventral striatum, and there's a release of dopamine when we're in socially interacting situations. And this, of course, makes us happy, and it fights off loneliness. So the neuroscience answer to loneliness is pretty straightforward. Interact with the world. Don't stay at home alone. Get out and talk to people. Now, on a personal note, I'll just say that you can have an impact too.

When you're out and about in the world, there's a lot of lonely people wandering around out there. And you can impact their lives, whether it's in the grocery store or if you're just out for a walk. Remember, just one simple hello or hey, how's your day going will cause positive changes in the brain. The other person's emotional system will respond. Their dopamine system will respond. And that will help stave off the loneliness that they might be experiencing. All right, that's what I've got for today, the neuroscience of loneliness. I hope you found it interesting. Remember, you can follow me on Twitter, thatneurosagguy.

I typically save my Twitter feed for stuff about my research lab and my day job, but there's some cool neuroscience stuff in there and you can hear about recent papers from the Kregolson Lab. We do have a YouTube channel. It's pretty small and I told you before, it's tied to courses I teach more than anything else, but there might be some bits and pieces in there you find interesting. And you can find our YouTube channel, that neuroscience guy on YouTube, of course. And of course you can email us that

neuroscience guy at gmail.com. And please, if you're listening to the podcast for the first time, please subscribe. It really helps. My name is Olive Kregolson, and I'm That Neuroscience Guy. Have a great week, and I'll see you next Sunday.