That Neuroscience Guy - The Neuroscience of Schizophrenia

Episode Date: April 3, 2023

Schizophrenia is a common brain disorder that causes delusions, hallucinations and disconnection from the world around you. In today's episode of That Neuroscience Guy, we discuss the neuroscience behind schizophrenia, and how brain dysfunction leads to the aforementioned symptoms. 

Hi, my name is Olaf Kregolsen. I'm a neuroscientist at the University of Victoria, and in my spare time, I'm that neuroscience guy. Welcome to the podcast. If you've ever seen the movie A Beautiful Mind, you would have met or at least seen the character of John Forbes Nash Jr., an American mathematician, professor at a university, PhD, who won the Nobel Prize in Economics for his work related to game theory and specifically something that's called the Nash Equilibrium. Well, that's not what I'm going to talk about today because if you watch the movie or you read the book, you would have learned that Dr. Nash suffered from schizophrenia. In the movie, Dr. Nash sees people that aren't there and has conversations with them. And that's kind of what schizophrenia is.

So on today's podcast, the neuroscience of schizophrenia. So there's a bit of confusion around schizophrenia. First of all, schizophrenia doesn't involve a split personality. So it's not the same as dissociative identity disorder, and that's what people commonly call multiple personality disorder, but it does get confused. And that actually goes back to the word schizophrenia because it was first coined by a Swiss psychiatrist back in 1911. And the word comes from a Greek origin that basically means splitting of psychic functions. And that's the part of that. So because of that, people sometimes get it mixed up, but it's not that. What schizophrenia actually is, is a psychotic disorder. It's basically one in which your thoughts,

perception, behaviors are impaired to the point where you can't really live a normal life. Now, people with mild schizophrenia can to some extent, but if you've got, you know, schizophrenia and it's more severe, you basically have a psychotic disorder and it means that you're disconnected from the world and you don't really function in the world the way most of us do. So what are the symptoms of schizophrenia? Basically, the most common symptoms are hallucinations, and I'll dive into that and talk about what's going on in the brain, and delusions. But people with schizophrenia also have disorganized thinking.

They have problems with their thinking patterns. They have what's called disorganized or abnormal motor behavior. And they have something that's called negative symptoms. And I'll go through all of these things and explain what they are and talk about what's going on in the brain. In terms of the first symptom, a hallucination, basically a hallucination is a perceptual experience. So your perceptual system is processing things, but it's in the absence of external stimulation. Now, the most common form of hallucination in schizophrenia is an auditory hallucination. It occurs roughly in two-thirds of the people with schizophrenia. And basically what that means is you hear voices, and you hear voices that aren't there.

So your perceptual system, and we talked about perceptual processing in the brain, basically is hearing things, but there's no actual external stimulus. The voices can be familiar or unfamiliar. It might be a voice of someone you think you know, but it might be a voice that you've never heard before. People with schizophrenia can have conversations or get into arguments with them. Sometimes people report that the voices are actually providing

like a running commentary on what's going on. So it's like someone's watching you and saying, yep, now you're touching your nose and now you're walking out of the room. And then that voice follows the person, which is why people with schizophrenia can tend to get angry because these things are constantly nagging at them. Although it was portrayed in a beautiful mind, it's far less common to have visual hallucinations and see things that aren't there.

And even less common is olfactory hallucinations and smelling odors that aren't actually present, although that can occur. So what causes a hallucination in schizophrenia? Well, basically, it's got to do with the brain, obviously. And what it's got to do is with the way the left brain and the right brain work in terms of belief systems. And we've talked about that before. The left side of your prefrontal cortex is effectively maintaining a worldview. And the right side of the brain is basically updating that worldview. And for most of us, this system functions normally.

But if this system is disrupted, and the brain isn't able to say, hey, that's not there, all right, you can't change your worldview. So what happens is this becomes a part of your worldview that this thing is actually happening. So the perceptual system is triggered. It's kind of like when we talked about dreaming during the sleep episode, your brain is creating perceptual stimuli. You know, in your brain, you've got all of these ideas. It's just normally the brain is the, you know, this left brain, right brain combination is locking it down so that these ideas don't seem real to you. But in schizophrenia, that system isn't able to do that. So the perceptual system is internally stimulated, just as it is, like I said, during REM

sleep. And you sense things that aren't actually there. Now, the second system was delusions. And delusions are basically a belief that you have that's contrary to reality. And you hold them even when there's evidence to go against that. So most of us, if you thought something extreme like a delusion, you would just quickly go, well, that's absurd. Now, a common example of this is people with schizophrenia might believe that someone is plotting against them, a co-worker, a significant other, even a stranger. You know, I've heard a story

about a man with schizophrenia who was convinced the person at the 7-Eleven was trying to poison them whenever they got something from 7-Eleven. And the reason this is a delusion is because the evidence is clear that that's not true. Okay. So people with schizophrenia experience these kinds of delusions. Other types of delusions can be more on the grandiose side of things. Some people with schizophrenia, for instance, believe they're a famous religious figure. Some of them believe that they've lived for 10,000 years.

Again, I've heard of a story of a person with schizophrenia believing that they were from outer space. And again, this is a delusion because all of the evidence is there that this isn't exactly true. And in terms of the neural basis of this, this goes right back into this left brain, right brain idea. You know, if you have a delusion and you believe that you're from outer space you know the right brain shouldn't update the world view and say hey this is true I actually am from outer space the left brain should actually win the argument and say no that's not true that's there's evidence against this so we're not going to do that so this goes back to this left brain right brain combination that we've talked about in the past the left prefrontal cortex maintaining your worldview and the right prefrontal cortex updating your worldview if

needed now the other symptoms of schizophrenia one of the things i talked about was disorganized thinking all right or or disjointed or incoherent thought process. Basically, what this comes across as, is people with schizophrenia tend to run on. They ramble. They jump from topic to topic. They say things that don't even make sense. The words come out in the wrong order. Now, to them, they believe it's true,

but if you were listening to them, you would say, well, this person is just randomly putting words together, but the person with schizophrenia doesn't get this and can't do this. And again, I hate to keep the story the same. There are some other pieces to it, but again, this is the prefrontal cortex. And this is this left brain, right brain combination. And in terms of some of the specifics of this, it goes a bit further than that. A key part of the prefrontal cortex is the dorsolateral prefrontal cortex,

what we abbreviate to the DLPFC. And what the DLPFC does is it's suspected to be where executive control occurs. And when you talked about executive control a long time ago, when I talked about memory, but basic executive control is our ability to stay on task. It's our ability to switch between tasks. It's our ability to problem solve. But it's our ability to control the brain and organize the brain. schizophrenia and they can't keep their thought processes or their stream of consciousness in line like people without schizophrenia would. I mentioned the fourth symptom was disorganized or abnormal motor behavior. Typically, this comes across with people with schizophrenia giggle a lot

or they might smile all the time. They might do very repetitive movements over and over again, odd facial expressions. And this is the, it's similar to the executive control issue, but it adds another part of the brain, which is the anterior cingulate cortex. And the anterior cingulate cortex plays a role in that disorganized thinking, but it also plays a role in this disorganized or abnormal motor behaviors. Because basically what the ACC does is say, no, that's not an appropriate action. Let's not do this. And if that process is disrupted, then you might giggle when it doesn't make sense to giggle because the ACC doesn't have the ability to turn that off.

So the ACC or anterior cingulate cortex. The fifth symptom I mentioned was what are called negative symptoms. And this is basically people that they don't have an emotional response. They generally just tend not to do much. They don't say much. They don't have an emotional response. They just sit there very quietly with sort of an absent looking face. And they don't have a lot of drive. This again goes back to the prefrontal cortex and executive control. And the story you might remember from your psychology undergraduate days, if you went to university, is the story of Phineas Gage. If you don't know the story of Phineas Gage, it's worth looking up. But essentially, I'm going to talk about that on The Bite on Wednesday, the story of Phineas Gage. But again, this is the executive control, the prefrontal cortex, which is because it's not functioning it properly, these negative symptoms can occur.

Now, what causes schizophrenia? Like, what is the driving force? Well, most of the evidence suggests that there's a genetic basis to schizophrenia. It's a problem that's still being solved. But we know, for instance, that people that have a parent with schizophrenia are six to eight times more likely to have schizophrenia. And the closer the person is to you, so if it's your parent versus, you know, your great, great, great grandfather, you're more likely to have schizophrenia. So the evidence strongly suggests that there's a genetic

origin for schizophrenia. But what does that genetic disorder or disruption do? Well, it's going to get to those brain levels, but there's an in-between piece. There is a ton of evidence that shows that in people with schizophrenia, the neurotransmitter dopamine that we've talked about in the past plays a crucial role in schizophrenia. And what ties it all together is that basically all of those brain regions I mentioned, the left and right prefrontal cortex, the executive control in the dorsolateral prefrontal cortex, and the ACC. These are all regions of the brain where dopamine is crucially important for proper

neural function. So if the genetic underpinnings of schizophrenia disrupts the dopamine, that's what causes these brain regions to function improperly and that's why the symptoms occur. And basically the other thing that's known with schizophrenia is that people with schizophrenia, if you put them in an MRI scanner and you look at the brain, you see that the ventricles of the brain, these are the cavities in the brain that hold the cerebral spinal fluid, basically these ventricles are larger than normal. And because of that, other brain regions are reduced in size. And that is what again causes this dysfunction. So two reasons for the dysfunction or the underlying root of the symptoms,

this impairment of the dopamine system, and the fact that the brain is actually reduced in size. And because of that loss of brain tissue, which you can actually see, there's a loss of gray matter in the brain. And specifically in the frontal lobes, which of course is where all of those brain regions are. And that leads to all of the symptoms that people see in schizophrenia. What can you do about schizophrenia? A good place to wrap it up. Well, basically you need a medical team. In mild cases, people with schizophrenia can work in the real world,

but most of the time, they're medicated, and the medications they're treated with are antipsychotic medications, and they specifically target the dopamine system to try to regulate the dopamine system. But in the extreme cases of schizophrenia, even that's not enough. So someone has to stay basically in a psychiatric hospital. And that's because although you can modulate the dopamine flow issues through using antipsychotic medications, that loss of actual brain tissue isn't something you can get back. And because of

that, most people with schizophrenia tend to need constant medical treatment. All right, there you go. The neuroscience of schizophrenia. I hope you found that interesting. I was actually watching A Beautiful Mind and I went, you know, there's a good topic. I want to dive into schizophrenia. Don't forget our website, thatneuroscienceguy.com.

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