That Neuroscience Guy - How Alcohol Impacts Your Brain

Episode Date: November 15, 2021

Alcohol consumption makes us feel and behave much differently than usual, and can often be addictive. In today's episode of That Neuroscience Guy, we discuss how alcohol impacts your brain and why you become addicted to it. 

Hi, my name is Olof Kergolsen, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. Back in season one, we did a couple of Q&A episodes, and people were really curious about alcohol in the brain. And we talked about it for a few minutes, but today we're going to take a deep dive. We're really going to go through the impact of alcohol and your brain. So, what happens when we have a couple of drinks? You know, what is alcohol we have a couple of drinks?

What is alcohol doing to our brain? Well, there are some obvious things. You might have noticed after a few beers that you stumble a little bit and you're a little bit off-kilt, if you will. Well, funnily enough, one of the brain regions that's really impacted by alcohol is the cerebellum. And the cerebellum is a key part of the brain in terms of the motor system. The cerebellum is really responsible for the coordination of movements and the timing of movements.

You know, it keeps you functioning smoothly, if you will. So when alcohol impacts the cerebellum and starts reducing its efficiency, our movements become more uncoordinated. Our timing is off. And that's why you stumble a little bit or you reach for something and grab and you might miss it. Because the cerebellum, just the way it's built, is really impacted by alcohol. just the way it's built, is really impacted by alcohol. Now, obviously, there are other brain regions that are impacted by alcohol. For instance, GABA is an inhibitory neurotransmitter, and it's impacted by alcohol.

And what does that do? Well, it's the thing that leads to slurred speech. It's not able to inhibit things that it should be inhibiting. And as a result, your speech is a little bit off. And funnily enough, it also gets you down the road to bad decisions. And GABA stops you from doing certain things that you probably shouldn't do. But what else? Well, it turns out there are a ton of things that are impacted within the brain by alcohol. For instance, vasopressin, it's a hormone and the change in vasopressin levels are why you want to go to the bathroom a bit more than you normally want to. Basically, alcohol's impact on vasopressin is why you want to pee a lot.

Now, it gets way more complex than that. In the past, we've talked about decision-making in the brain, and we've talked about the prefrontal cortex. Just as a reminder, the prefrontal cortex is that part of your brain that does your analytical decision making. It evaluates the options, if you will. And if you think back to our decision making episode, it's going through the values for choices. You know, should I do this? Should I do this? What's it worth to me if I do this? What's it worth to me if I do that? And that's what the prefrontal cortex does.

It engages when we're not on autopilot. It's what Daniel Kahneman calls system two. It's this high-level analytical decision-making system. It's also responsible for what we call executive control. Our ability to switch between tasks, our ability to focus on goals, our ability to make decisions, as we've said. Now, what does alcohol do to the prefrontal cortex? Well, simply, it just shuts it down. So, as you're drinking alcohol, what you're literally doing is turning off your analytical decision-making system.

is turning off your analytical decision-making system. Yep, you're literally shutting down the part of your brain that's going to stop you from making bad choices. The part that's going to say, you know, maybe I shouldn't do that. In fact, sadly, this is why people drink and drive. You should never drink and drive, of course. It's the worst idea ever. As we've already discussed, you've turned off your motor system, you've got slurred speech, you've got the need to pee more. And what are you doing on top of that? You're literally shutting

down your analytical decision-making system. So your body's responding to alcohol with all of these things we've talked about. And normally what you should do is go, well, I won't drive today because my body is not responding the way I want it to. But you're turning off that system. So shutting down your prefrontal cortex is one of the reasons we make all the brilliant decisions we make when we've been drinking. And it gets worse. While the prefrontal cortex is being shut down, the amygdala and your emotional system, it's getting ramped up. The impact of alcohol on these brain regions is to amplify the responses. So think about what that actually means. Your emotional system, which is sensitive at the best of times, is all of a sudden being told, let's respond to everything as big as we can. Let's amplify every response. That's why you cry more. You get more emotional. It's why you laugh more, it's why you might feel a bit amorous.

So alcohol, at the same time, is shutting down your logical decision-making system in the prefrontal cortex, but it's also dialing up your emotional responses. I don't think you need me to walk you through why this is a problem. You're literally turning off the part of your brain that's saying, don't do it. And you're amplifying the part of your brain that's saying, yeah, go for it. Now there's more to it than that, of course. Why do we do it? Like, why do we drink alcohol? Well, it goes back to our old friend dopamine. In fact, I almost want to rename this the dopamine podcast, because dopamine plays such a crucial role in brain function. Now, in terms of alcohol, if you think of dopamine and what's happening, well, if you remember prediction errors, when we talked about learning, your brain is constantly

computing, how are things going? How are things going, how are things going? And it does that by comparing outcomes to expectancies. An outcome is the result of an action. It's a reward, if you will. And your expectancy is your belief that that's going to happen. So what's happening with this system? Well, when you take a drink, things all of a sudden are better than expected. So there's a release of dopamine and your brain processes that as a reward. So it wants more. If you think back to

our second episode, this is why social media is addictive. Every time someone gives you a little like, well, it's a little release of dopamine and things are better than expected and you want more of it. Well, this is what's true with alcohol. You take a sip and all of a sudden things are better than expected. You're happy and you're like, wow, okay, this is cool. This is the problem. If you think back to how the system works, we learn about these expectations. The whole point of these prediction errors is to change the value of choices. So you increase the value for having a sip of alcohol and all of a sudden your outcome and expectation are equal.

So there's no prediction error, but the problem is there still is that pleasure or happy response. So what do you have to do? You have to increase the amount of reward to keep these prediction errors happening. You have to keep making things better than expected. So what does that mean? Well, sadly, that's why you drink more and more and more. Because you're literally increasing these values so that you keep having prediction errors, which triggers this dopamine release, and you become addicted. And this is the addictive mechanism for alcohol, and to be fair, a lot of other things. This idea that our outcomes and expectations all of a sudden are aligned so we need to make the outcome bigger and in terms of alcohol that just means you keep drinking more and more and more and you keep doing it because you keep wanting that dopamine release and all of a sudden you're

addicted and this is why people become addicted to alcohol. Because they keep wanting those little prediction errors. Of course, alcohol has a negative impact in a lot of ways. Perhaps one of the biggest ones, and one of the saddest from my point of view, is fetal alcohol spectrum disorder. This is why we tell people, don't drink when you're pregnant. You have to remember that when someone's pregnant, and we'll probably do an episode on the neuroscience of pregnancy at some point,

at the end of the day, there's a child inside of someone, and that child is dependent on the blood flow, the oxygen, the nutrition from the body that's hosting it. And when you drink alcohol, well, that alcohol flows in to the fetus and that's literally what FASD is the impact of alcohol on a fetus that's not prepared for it the fetus doesn't have the ability to process alcohol I think we all know that your liver plays a key role in this processing alcohol and trying to push it out of your system. Well, the fetus doesn't have that level of protection. And sadly, what FASD really is, is brain damage. The impact of

alcohol on the unprotected fetus is brain damage. So if I say one thing in this podcast where I'm going to lecture you and try to make your life better. Please, if you happen to be pregnant, don't drink. You're causing brain damage to a young child that can't even protect itself. I guess the final piece of the puzzle is the hangover. I have to admit I've had a few beers myself sometimes, and sometimes I have too many, and you experience the hangover. Well, if you think about what we've been talking about, your prefrontal cortex isn't working that well, so it's not making great decisions. Your emotional system is ramped up. Your motor system, because of the impact of alcohol on the cerebellum, is not functioning as well as it could. And on top of that, your blood sugar is going to be low.

You have a lack of water within the body and the impact of water is massive. You're dehydrated and that means your body's not functioning as well as it can. And of course, there's the toxicity of it. So a hangover and the neuroscience of hangovers is simple. All of the things you really need to function effectively, blood sugar, water, not having toxins in your body. Well, they're all present and your body processes it. Slowly, your body goes through the motions in it. You know, let's get rid of this. Let's get rid of this. Let's get rid of this.

and that's why, you know, to be fair, the best thing you can do for a hangover is just sleep a bit more and drink a lot of water because you just have to let your body recover. Let's take it from the top. First things first, cerebellum being shut down. That means your motor system is impacted and you're uncoordinated. You're stumbling a bit. GABA, that inhibitory neurotransmitter, slurred speech, leads to bad decisions. Vasopressin, hormone, makes you want to go to the bathroom more. The prefrontal cortex, you're turning off the part of your brain that makes analytical decisions. And at the same time, your emotional system, the amygdala and all the connected pieces, you're wrapping that up. system, the amygdala and all the connected pieces, you're wrapping that up. And of course,

there's this idea of dopamine and reward. You keep wanting to keep doing it because you're looking for more and more rewards. So there you go. That's the neuroscience of alcohol and how it impacts our brain. My name is Olof Kregolsen, and I'm That Neuroscience Guy. Thanks for listening, and I'll see you next week. And by the way, make sure you check out our YouTube channel, That Neuroscience Guy. You can follow me on Twitter, That Neurosci Guy. And of course, please listen to the podcast and tell your friends all about it. Thank you very much. See you next week.