Instant Genius - The psychology of anger

Episode Date: November 22, 2024

It’s likely that even the most virtuous amongst us has experienced feelings of anger at some point in our lives. But is this simply a failing in our personal moral fabric or does it have more universal biological origins?   In this episode, we catch up with Guy Leschziner, a professor of neurology and sleep medicine at King’s College Hospital in London to talk about his latest book Seven Deadly Sins: The Biology of Being Human.   He tells us how activity in the emotional regions of our brains affects our behaviour, talks about the influence of testosterone on our aggressive tendencies and tells us how mutations in specific genes can predispose us to commit violent acts. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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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. Every Monday and Friday, you'll hear world-leading experts and scientists talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. It's likely that even the most virtuous amongst us

has experienced feelings of anger at some point in our lives. But is this simply a failing in our personal moral fabric? Or does it have more universal biological origins? In this episode, we catch up with Guy Lechziner, a professor of neurology and sleep medicine based at King's College Hospital in London to talk about his latest book, Seven Deadly Sins, The Biology of Being Human. He tells us how activity in the emotional regions of our brains

affects our behaviour, talks about the influence of testosterone on our aggressive tendencies, and tells us how mutations in specific genes can predispose us to commit violent acts. Welcome to the podcast. Thanks very much for joining us. It's lovely to be with you. Today we're talking about your latest book, Seven Deadly Sins, the Biology of Being Human. It's a really interesting topic. So what's the premise of the book? Well, the premise of the book is that we have historically grown up in a Judeo-Christian society

that characterizes bad behavior as all originating from the Seven Deadly Sins. And, you know, this has very much been a marker of morality, the measure of what makes a person good or bad. In my clinical practice, and indeed probably the clinical practice of every medical professional who works in the sphere of brain health, we very regularly see individuals who have brain injuries or brain trauma or tumors that actually results in dramatic changes in their personality and their actions. and, if you will, sinful behaviour. So that tells us very obviously that actually the origins of these behaviours are in the brain,

at least for those individuals. But actually it tells us much more than that. It tells us that it's in the brain for all of us. And so what this book does is it looks at those examples of individuals who have had changes in their behaviour that meet the criteria of the seven deadly sins as a result of illness or disease, and how that applies to all of us, really making us question whether or not we have full control over our behaviour and whether we should be looking at

these kinds of actions in a slightly different way. So this is what you mean when you say sin is less of a moral question and more of a biological one. Exactly, yes. So let's talk about the deadly sin wrath or anger. So in the book you talk about the neural roots of anger. What do you mean by that? So when you look at individuals whose behaviour has changed, who have become more wrathful, more aggressive, more violent, there are really two major areas of the brain that can result in these kinds of changes. The first is the emotional circuitry, the circuitry that's responsible for generating and heightening our emotions.

And then there is a second brain region, which is a region of the brain called the prefrontal cortex, which essentially is the bit of the brain that acts as a break for our emotions. It acts as a calculator of circumstance as an aspect of our reasoning and regulates it. And so there is this constant interplay between the parts of the brain that generate anger, and indeed many of other emotions, and the prefrontal cortex, which reigns in. And you call the prefrontal cortex the seat of humanity in the book? Well, I call the prefrontal cortex the seat of humanity because essentially if one looks at the very complex social skills that we have, if you look at how we interact with each other, how we reason, how we perform rational thinking,

all of these origins are within the prefrontal cortex. And what is quite different between us and our closest relatives, chimpanzees and other apes, is this, firstly, this massive expansion of the prefrontal cortex, but perhaps more importantly than the expansion is actually its organisation. And it's really this part of the brain that differentiates us from other animals. You break down aggression into different types, reactive and proactive. What's the difference there? So reactive aggression is that kind of violence that is a response to the heat of the moment when you, your family, your resources are threatened. And obviously reactive aggression is very widely seen throughout the animal world.

But where we particularly excel is in what's termed proactive aggression, which is aggression that can, of course, be associated with threat, but is a bit more calculated. It's a bit more cold and it has ulterior motives. It's the sort of aggression that is linked to, for example, making sure that you attack somebody when they are at their weakest, with planning, with things like that. And that's where we, unfortunately, is human to really excel. So we've talked about the prefrontal cortex, but you also talk about another area of the brain called the amygdala. What role does that play? So the amygdala is a part of the brain that is a crucial component of a brain circuit called

the limbic system. And the limbic system more widely is really the bit of the brain that is most strongly associated with the generation of emotions. The amygdala can be considered the fear center of the brain, the bit of the brain that processes threat and the emotional response to threat. And when I talked about the balance between the parts of the brain that generate emotions and the prefrontal cortex which suppresses or reigns them in, it's really the amygdala when it comes to Roth that has been most closely associated with anger and aggression.

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A lot of people talk about testosterone in the context of aggression. What role does that play? Well, that's a really interesting and complicated question. So we know that actually absolute levels of testosterone between individuals, do not necessarily predisposed to violence. Of course, you know, for pretty much all mammalian species, apart from one or two, violence or aggression is associated with males much more than females. We know that testosterone has got some really interesting effects on the developing brain

when we're still in our mother's womb. So one of the ways in which you can monitor or at least assess exposure of the fetus inside the mother's womb to testosterone is in a really unusual way. So if you look at your index finger and you look at your ring finger, particularly on your right hand, and you look at the ratio between the finger lengths, that gives us some measure as to the amount of testosterone we've been exposed to in our mother's womb. So the more testosterone you've been exposed to in your mother's womb, the longer your ring finger is in relation to your index finger. And if you use that finger length ratio, what you see is some startling results in that actually those people who have a particularly

long ring finger are people who are often going to exhibit, for example, more anger in a video game or exhibit an increased predisposition to anger in a series of scenarios in the psychology lab. So it seems that testosterone has got a fundamental impact on the developing brain that might predispose to anger. We also know that testosterone is a hormone that responds to success. So if you win at a sport, even if you win at chess, for example, which is not particularly known to be associated with, you know, huge amounts of emotion, testosterone surges.

And one of the theories is that testosterone is a hormone that is fundamentally important to males in particular in terms of driving them to success, driving them, you know, in evolutionary terms to sexual success. And of course, as part of that, being aggressive, being able to defend yourself against other rivals is going to be crucially important. So let's have a look at genetics then. In the book, you mentioned something known as the warrior gene. What's that? So the warrior gene is one of the earliest genes that has been directly associated with aggression. This is a gene called M-A-O-A, and it's responsible for the breakdown of a range of different brain hormones of neurotransmitters, neurotransmitters like adrenaline and

noradrenaline. And in the last century, it was identified that there were families in which there were significant mutations in this gene, and for males in particular, because in females, because it's an excellent gene, they tend to have two copies, whereas men only have one. If you have a mutation as a man of this gene that essentially knocks out this enzyme that breaks down adrenaline and noradrenaline, your aggression levels are very, very high. In fact, individuals with this particular mutation are at very high risk of committing violent acts like rape, like arson and murder. Now, that also, obviously results in a complete absence of this enzyme, but what we've learned over the

subsequent years is that there are particular genetic variants within this gene that also can influence our levels of aggression. So, you know, it's a bit of an irony that aggression arises from aggression. So what I mean by that is that there are, you know, very clear bodies of literature that show that aggression in adult life is often associated with exposure to what is termed childhood adversity. So these are individuals who live in a stressful environment, an environment that is rich in physical trauma, psychological trauma, sometimes even sexual trauma. And it appears that actually being in a stressful environment in childhood predisposed poses you to brain changes that influence your levels of anger and your predisposition to violence.

Now, some of that is probably related to the fact that when you live in a perpetually stressful state, your levels of cortisol are high. Cortisol is the principal stress response hormone in the body. And cortisol and other steroids have very fundamental effects on brain development and brain growth. In fact, there is some evidence that actually even if your mother lives in a stressful environment when you're still in the womb, that can influence you in later life as well. Coming off the back of that, then, how about this notion of epigenetics? So epigenetics is this idea that although our genetic code is written in stone,

as we go through life, that genetic code is modified, usually through a variety of different mechanisms, Essentially, what is happening is that little bits of molecules are added to our genetic code that influence how our genetic code is translated into the real world. And there is increasing evidence that exposure to our environment, both in the womb and later on in life, can affect our genetic code not by changing it wholeheartedly, but by modifying it and modifying how that genetic code is translated. And it seems that this is probably one of the important mechanisms by which our environment has a fundamental effect on how we develop and in particular how our brains develop. So let's have a look at some of the brain injuries that you mentioned in the book.

So the kind of poster child of this is Phineas Gage. Yeah, Phineas Gage was one of the most famous early cases from the neurological literature. He was a chap who in 1848 was working on the railroads in Vermont, in the east coast of the state. And one of his jobs was dynamiting away embankment. And he was, on one fateful day, he was tamping down a explosive in a hole that had been drilled with a tamping iron, which is a very large, long piece of iron. And unfortunately, he was a bit too rigorous in his tamping the explosive down and ignited the explosive in the hole. the tamping iron basically flew up from the hole under his chin and exited the top of his head and essentially caused quite significant destruction of his frontal lobes.

So what's really remarkable is that, you know, in the days before antibiotics, he survived this terrible injury. But what's even more remarkable from a neurological perspective is that Phineas Gage, according to reports at the time, and it's probably been over-eged a little even since the injury, self. He, prior to the injury, he was apparently a god-fearing man who didn't drink, he didn't smoke, he was polite to everyone, he was a delight to have around. And then after this brain injury, although his intellect was completely intact, he became a really rather unpleasant character by some accounts. He began whoring and drinking and began to indulge in petty crime and became sexually disinhibited, you're really giving us one of the first indications that specific areas

of the brain have very specific functions. And in his case, demonstrating that the frontal loaves, particularly the prefrontal cortex, which was taken out by the tamping iron, is responsible for reining in some of our antisocial behaviour. So moving up to the present, there's a lot of talk at the moment about traumatic brain injury. So what is that? So, Traumatic brain injury is really any form of mechanical injury to the brain. And, you know, in some people with very major trauma, we see massive bleeds or significant bruising to the brain. And others, we see relatively little change. The reason why this is particularly relevant to Roth is that we, for example, if you look at prisoners and you look at violent prisoners in particular, you see that in violent prisoners, they often have areas.

areas of damage to their frontal lobes in comparison to prisoners who are non-violent. We know that traumatic brain injury is very strongly associated with violence or aggression later on in life. Now, of course, there is an explanation that if you are inherently violent or aggressive, you're more likely to accrue a brain injury. But even if you look at children who have traumatic brain injury, and that probably is less of an important fact of children, you know, traumatic brain injury in children is often associated with increased criminality and increased aggression. Now, why that should be the case? Well, of course, if you have damaged your frontal lobes, then you're much more likely to be socially disinhibited.

You're much less likely to be able to plan rationally. You're less likely to be able to inhibit some of your other behaviours as well. And this is a major public health issue because, of course, traumatic brain injury or TBI is very common in the population. It's one of the commonest causes of significant mortality and morbidity for young people in particular. And this may be an important contributor to violence and criminality in our society. You also talk about a case study of someone who suffers from epileptic seizures, and for want of a better term, often finds himself losing control? Well, I think historically, incorrectly, quite frankly, epilepsy has been associated with violence, and this stems from, you know, really early thoughts about what the basis for epilepsy was.

We actually know that violence is incredibly rare in epilepsy, but there are really a few specific circumstances in which it can arise. Actually, the commonest way that it can arise is through what we do, so it's doctor's fault. But what I mean by that is that there are some anti-epilepsy, medications that we quite routinely use that are very effective. The reason why we use them routinely is because they work very well. They're usually very well tolerated and they don't have a high likelihood of dangerous effects. But what these particular drugs can do is they seem to have a major side effect, which is irritability or regression in some people. Why that should happen, we don't fully know. It seems likely that these antiseasure medications,

fundamentally alter the neurochemistry of particular brain regions like the limbic system and can generate these sorts of rage attacks in particular individuals. So I think the most striking example that I've ever seen is of an 80-year-old lady who was sweet as can be who, after being started on this drug, ended up being arrested by six burly police officers sitting on top of her in her front garden. So it can be very striking indeed. There are other reasons why epilepsy can rarely be associated with violence or aggression. Firstly, if you've got seizures that arise in close to the limbic system, sometimes fear or anger

can be a part of the seizure itself. So essentially what seizures represent is abnormal, uncontrolled electrical activity in a particular part of the brain. And if you imagine that all of a sudden your limbic system goes into overdrive, then you can begin to understand why fear or anger might be part of that seizure. The other situation is really in what we term the post-dictal state. So often individuals after having had a seizure become quite markedly confused because their brain is not working properly. There's a whole range of electrical and chemical changes that happen in the aftermath of a seizure. And that sort of confusion after

a seizure, which at its most extreme can even manifest as psychosis, so people hallucinating or being delusional can result in violence as well. Another case study you mentioned in the book is someone who suffered a brain hemorrhage that significantly changed their personality. Well, in many respects, there are some parallels between somebody who's had a brain hemorrhage and other forms of brain injury, be that a tumour or be that a stroke, or be it traumatic brain injury. Essentially, this chap had what was termed a subarachnoid hemorrhage, where he had bleeding into the lining of his brain rather than the substance of his brain,

but he was very clearly left with significant deficits. He had profound anger associated with fear, so often precipitated by threat, even very minor perceived threat, that really led to a wholesale breakdown in his life and what he was able to do with his life. It actually ended up causing him quite a lot of trouble in his life. Now, why that should be the case? Well, I think it probably depends on which areas of the brain are affected. And in his case, he was rather unlucky and probably sustained some damage both to the limbic

system and to the prefrontal cortex. So not only did he have increased aggression, but probably also had an inhibited ability to dampen down that aggression as well. So how about the effects of alcohol? In the book, you mentioned the number of violent acts committed by people, under the influence of alcohol is incredibly high. Well, I think there remains some ongoing debate as to whether or not alcohol unmasks underlying aggression in people, who by their nature probably have heightened levels of aggression

already, or whether alcohol in and of itself can cause people to become aggressive. I think that question has not been answered yet. But what we do know, that one of the effects of alcohol is that it causes a reduction in front-lobe function. And, you know, one of the ways in which it works and one of the reasons why we enjoy it so much is because we become disinhibited. Those, you know, social behaviors that we are attuned to that we keep on as a facade in our day-to-day life are released by alcohol. But unfortunately, one of those social behaviors is also the suppression of aggression. And so essentially what you're doing is you're taking the breaks off.

the brain. So by way of summing up then, obviously aggression and anger are both parts of the human experience. But why do we have them in the first place? Well, I think this is the case with all of the sins, is that essentially all of the sins are patterns of behavior that have evolutionary advantages. You know, they are healthy in moderation. If you think about the evolutionary pressures that have been placed upon humans and indeed all animals over the millions of years of which we've been evolving, to defend your resources, to defend yourself in the face of threat is actually a very important survival behaviour. And if you look at anger in the modern world, we also know that anger is an important driver of success. So if you give people a

very difficult puzzle to undertake and you make them angry before you give them that puzzle, they're much more likely to persist for longer and they're much more likely to achieve resolution of that puzzle. So essentially anger is an important emotion that drives us to clear any threats from our ultimate goal. The issue is really in our human societies is when that anger turns to aggression, and that's when it causes harm. But the same can be said for lust or for gluttony or for any of the other sins, that all of them serve a very useful purpose. It's just that when things go awry, that they create problems. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Professor Guy Lechstner.

To discover more about the topics we've just discussed, check out his book, Seven Deadly Sins, The Biology of Being Human. If you liked what you just heard, then please do consider subscribing to Instant Genius on your preferred podcast platform. The current issue of BBC Science Focus magazine is out now. Pick up a copy wherever you buy your favourite magazines or download us on your app store of choice. You can also find us on Apple News or online at sciencefocus.com. This podcast is sponsored by. by Name, Audio and Focal.

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