That Neuroscience Guy - The Neuroscience of Middle Age

Episode Date: July 24, 2025

In today's episode of That Neuroscience Guy, we discuss how your brain changes throughout middle age. 

Hi, my name is Old Craig Olsen and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. So it's the day before my 55th birthday. And in the spirit of that, I came up with a topic that I wanna talk about, because it's one that we don't talk about that much in terms of neuroscience or psychology or just in general.

So I know we were doing sensory processing, but I'm just gonna take a quick break and talk about the neuroscience of middle age. So like I said, I'm about to turn 55 and when we talk about the brain, it's sort of weird because we generally talk about a brain that exists only in the 18 to 25 population. The majority of neuroscience and psychology research is targeted at that specific age group. And that those, because the reality is it's when we recruit participants

for our studies, we generally just test people that are on campus, and guess what? The majority of people that are on campus are in that age group, 18 to 25. And I could go down a rabbit hole tangent there about how that bias is science, but I won't. Now to be fair, there are labs that look at the younger people under the age of 18 to 25.

So they deliberately go out and look at infants and children and teenagers. And there are labs, including my own, that go out and look at the aging population, you know, the 65 plus group. But what about the 30 to 55, 60 crowd? You know, I Googled this because I was curious, what's the 30 to 55, 60 crowd? I Googled this because I was curious

what's the definition of middle age, and it's a bit debatable, but they sort of say 45 to 65. I'm gonna be optimistic and go with that because I'm 55, so it puts me in the middle of middle age. But I thought I'd talk about the changes that go on the brain in my age group. So what's happening, call it from the age of 30

to the age of 60. So on today's podcast, the neuroscience of middle age. Okay, there's a whole array of changes that happen. Basically, the brain continues to grow in a variety of ways until you're sort of in your early 20s. No one knows exactly for sure and what I like to tell my my students is from the time you're about their age you know in your early 20s your brain's dying. You start to lose 20 to 25,000 neurons a day and there's not much you can do to slow that. You can sort of try to

keep it at that number and you can obviously accelerate it through concussions or alcohol abuse or any number of other factors. So your brain is slowly dying. As a result of that in middle age, your brain volume decreases. So the overall volume of your brain, especially in the prefrontal cortex and the hippocampus, all right, starts to go down. All right. So in terms of the prefrontal cortex, that's executive function of course, and that's why we're just not as sharp as we were in our early 20s. I know that we like to feel that we are, but the reality is those young kids have something on us, but what they don't have is experience. So defending the middle-aged group,

we have the advantage of experience which might make our decision-making better, even though in theory our executive function is reduced. And the hippocampus decreasing in volume means memory is impacted, especially the formation of long-term memories. Now we know that memory declines with age, and that's true, and of course that's natural. What we don't want is enhanced decline, which would be mild cognitive impairment. Now this begins subtly in your 30s, so brain volume starts to go down slowly but surely, and then it accelerates basically after the age of 60. So once you get past 60ish, alright, that brain volume decrease starts to happen even more rapidly, which is why if you could keep the physical body alive and slow down physical aging, you would have to somehow slow down brain aging as well. The cortex itself gets thinner, so that's the outer layer of the brain.

Again, the frontal area is struck in the temporal lobes. Basically, what that means is that it's just a loss or a decrease in brain function. So your overall brain function will be reduced because the cortex is thinner. So the actual pyramidal neurons that do all the computations, they're not as efficient as they used to be. You get a decline in white matter, all right. Again, particularly in the frontal lobe, the frontal lobe is attacked the most, if you will.

And then white matter is communication, right? This is the way information passes between neurons, which is why literally you might feel like you're thinking a bit more slowly. Now, the actual change is very small, but it means that the communication between brain regions isn't as fast as it was when you were young, in your 20s. And the last structural change that we see

is enlargement of the ventricles, all right? So these are the fluid-filled spaces in the brain, all right? And they basically get bigger. One of the reasons they get bigger is that you have a loss of tissue. So they're just growing to fill in the space if you will. So it's not like there's empty space within your brain. So as brain volume goes down, ventricles grow, get bigger. There's nothing really negative about that. The negative is of course the loss of brain volume.

Next we'll talk about the cellular and molecular level of this. Basically you get reduced neurogenesis. So there's not a lot of new neurons being formed in the brain. There was debate about this for quite a while, but now it's sort of accepted that in the hippocampus, neuron formation does occur throughout the lifespan. But in this still happens, it just slows down. So the neurogenesis in the hippocampus is just happening at a reduced rate. Although it does continue until we die, you can still form new neurons in the hippocampus. It's just slowing down. So during middle age, this process

is slowing down. We get a loss of synapses. So if you remember when we form new memories we're making new connections, new synapses are formed, and we get a decrease in the overall number of synapses basically. And this is reflected as learning isn't as efficient as it used to be. So when we learn we form new connections. When we're young, of course, we can do this. We learn so quickly, right? And we know that from the teenage years, the early 20s, is when you're learning all these new things and you can learn quickly, you can still learn right until you die. It's just it happens at a slower rate because you have synaptic loss, all right? And then in our memories affected the

same way. So the breaking of these synapses, all right, the breaking of the connections, the decrease in the number of connections, basically is reflected as a loss of memory as well. And finally, our neurotransmitters are affected. So all of the neurotransmitters, we've talked about dopamine, acetylcholine, serotonin, norepinephrine, glutamate. We basically get a reduction in the amount of these neurotransmitters. So this impacts our mood, it impacts our motivation,

it impacts cognition in general, all right? So while we're having all these physical changes, we're also having this reduction in the amount of neurotransmitters that are available, which means that our brain function is impacted as well. Now, these structural changes and these cellular changes results in functional changes, so changes in cognition. Probably the biggest one is, and this is kind of obvious, but and I've mentioned this already on this episode, but there's slower overall processing speed. All right, due to the decreases in neural transmission

rates, it's just slower to process things. Now people like to take this to an extreme. It's not like you sit there pondering for 10 minutes. That's just a recall problem. But overall you're a little bit slower to react. You know where I actually see this is playing video games with my son. My son is 17 years old. You know he's at the peak of brain function or getting close to the peak of brain function. When we're playing a video game, yes his hand-eye coordination is a bit faster, but he's literally processing the information in the game at a faster speed than I am, which gives him an advantage. So I guess parenting tip, don't try to play video games

with your kid. There was a point where I was better, it's long gone. You get a decline in working memory and episodic memory. So we've already sort of said this. So in terms of working memory, you know, working memory is when you bring things out of long-term memory and you use them, or when you're trying to encode new information. It just doesn't work as well. Alright? And again, it's because of these structural changes and these cellular changes. And our ability to recall specific events, it's just harder again, because of the changes in the hippocampus, the changes in the prefrontal cortex. It's just harder to do these

things. Executive function goes down, whether we like it or not. All right, our ability to plan things is impaired. Our decision-making is impaired. Our multitasking becomes more challenging. But I want to put a big caveat here. You can't replace experience. So while from a technical perspective, if we talk about decision-making, in our early 20s the prefrontal cortex might be in a better place to make decisions. If you don't have the experience, that whole value process, and again, if you forget the value idea, just go back and find an episode on decision making. We've talked about it a lot, but your value assessment is based largely on experience.

So with experience, even though the process might be a little bit slower because of the changes in the prefrontal cortex in middle age, guess what? You're probably still better at making decisions because of experience. And what's interesting is as we head into middle age, what happens is we get more bilateral activation. This is a compensation. This is the brain trying to compensate for deficits. I'm not a big fan of lateralized brain activity. I've ranted on the podcast about this idea of left brain, right brain, which is largely nonsense. Again, if this is the first time you've heard me say that, we have an episode on hemispheric specialization where I walk you through that.

But what happens when we're older is we do rely more on the right side to help the left and the All right, so the brain is trying to borrow resources from other parts of the brain to do that. Now, what's important to realize as we hit middle age is that these changes are normal, all right? A reduced ability for task planning or for making decisions, impairments in memory, this is perfectly normal. And the best definition of this is if these changes

don't interfere with your daily life, you're okay. It's normal to be a bit forgetful. We're forgetful when we're young. I watched, I'm not trying to pick on my son today, but I watched my son try to find the car keys the other day and he had no clue where he'd put them down. We forget things throughout our life. As we get older, we get worried

that it's becoming more common, and it is. It's becoming a little bit more common. But if it's not interfering with your daily life, all right, that's just normal aging. Pathological aging, all right, is when you start getting mild cognitive impairment or dementia, and basically what happens, and we've got episodes on those,

so I don't wanna go into it in too much depth, but in that case, the age-related changes are so severe that they're impairing or interfering with daily life. Alright? And you might find that you're in a place where you your inability to remember something actually impacts daily life or you're not able to make a decision to do something. And at that point that's pathological aging and that's probably where you want to you know speak to your doctor and say well hey you know I know my brain slowing down a little

bit but I think it's a little bit this is a little bit more than what I would expect. Anyway hopefully you found that interesting I'm sure the young people that listen are going yeah yeah yeah middle-aged whatever and the people that are old are looking back at at middle age going yeah I remember those days but for those of us in the middle, I wanted to talk a little bit about the neuroscience of middle age. So there you have it.

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