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The Dose Transcript for February 22, 2024

Host: Brian Goldman

BRIAN GOLDMAN: Hi, I'm Dr. Brian Goldman. Welcome to The Dose. Well, some topics we do on our podcast are for you. This one just happens to be for me. I have never been an ace at remembering names. I would say I'm kind of average, but I have noticed that as I get older, it's getting a lot worse. And lately, the tip of my tongue is the focal point of my growing anxiety that my memory is failing me. True, as we age, our ability to store and retrieve memories isn't what it used to be. But how important is that? A lot of people have been thinking about this because Joe Biden and Donald Trump have had notable public memory gaffes. So this week on The Dose, we're asking, what happens to my memory as I age? Hi, Natasha. Welcome to The Dose.

NATASHA RAJAH: Hi, Brian. Thanks for having me.

BRIAN GOLDMAN: So what are some of the memory troubles that you experience?

NATASHA RAJAH: So I am a middle aged female, and so a lot of my memory troubles really is interference and lack of attention. So I sometimes walk into a room and I forget, you know, why I walked in. Or I open up my email to send something and I'm like, who was I supposed to email? So I definitely have some attention issues at the moment due to the constant demands on life that we experience at midlife.

BRIAN GOLDMAN: Can you give us a hi, my name is? Tell us what you do and where you do it. Just adlib.

NATASHA RAJAH: Sure. I'm a professor of psychology and a Canada Research Chair Tier one in Sex, Gender and Diversity in Brain Health, Memory and Ageing at Toronto Metropolitan University. I'm also an adjunct scientist at the Rotman Research Institute and adjunct faculty at McGill, where I was for 18 years previously.

BRIAN GOLDMAN: So you are obviously well qualified. At what age do problems with memory typically begin?

NATASHA RAJAH: So it depends on how you test for memory. So there's different memory systems, and some types of memory show decline earlier in our adult lifespan than others. But usually, when people talk about memory and they talk about concerns about memory, they're talking about episodic memory, which is our memory for past personal experiences. And that type of memory, there's a bit of debate. Some people argue that it starts to decline from 20 to 40, in your midlife, and then there's a steeper decline in older age, while my research has shown that memory of this type remains relatively stable until midlife and then starts to slowly decline at midlife and then accelerates in older age.

BRIAN GOLDMAN: So there is a moment when it crashes?

NATASHA RAJAH: On average, yes. But I just want to highlight that there's quite a lot of individual variability in memory function, and there are people called maintainers. So individuals that even in older age maintain their memory function and perform equivalently to young adults on memory tasks. So not everyone declines. There are people that are maintainers. There's people that decline steeper. They're called decliners in the field. And then there's also people that show some average decline, but nothing notable.

BRIAN GOLDMAN: It's often assumed that our memory gets worse with age, and there's a lot of evidence to show that that's true. But what really happens to our memory as we grow older?

NATASHA RAJAH: So as I mentioned, there's multiple different types of memory systems and some memories, so we have memory for facts and knowledge which we call semantic memory, and then there's our past personal experiences which we call episodic memory. There's some evidence that in healthy ageing or normative ageing, semantic memory actually might increase as we age because we're acquiring new world knowledge, and that's being maintained across the lifespan. However, our episodic memory, our memory for our past personal experiences decline with age. Now, within episodic memory, there's the memory for what you're paying attention to, which we call item memory, and there's also memory for the associated context. So contextual or source memory. And what we know is that with age, source memory specifically, so our ability to remember the perceptual, spatial, temporal details about our past experiences are particularly sensitive to the effects of ageing. Whereas memory for items such as seeing someone at a grocery store and knowing their name or knowing that you know them remains relatively intact into older age.

BRIAN GOLDMAN: And I'll just happen to tell you that while I have difficulty naming the name in the moment, particularly when I'm a little anxious and I feel like I'm being tested, I remember 20 or 30 contextual details about that person, so then everybody else can figure out who it is that I'm talking about, even though I can't name that person. So that's a real thing, isn't it?

NATASHA RAJAH: Yes, that is a real thing. And, you know, the tip of the tongue phenomena, that actually does increase with ageing. But what's funny is that the memory is actually there. It's more about interference and changes in attention and executive function. It's not necessarily a memory problem.

BRIAN GOLDMAN: So what are the interference factors in our practical daily lives that would make that tip of my tongue just seem so prevalent these days?

NATASHA RAJAH: So the more you encounter certain events or certain people, you have many interference, like many other memories with them, or many other memories with people that are similar to them. So your brain is organized like a neural network, and so things that are overlapping and similar will share some space in that neural network. And so when you see a person and they serve as a retrieval cue, there are other people that might also light up and their names might also light up. And so as a result, you might pick the wrong name to say, or you might pick the wrong country to say, for example. But it's not because of a primary memory issue, but is basically an issue with selecting the right answer. So it's more of an executive issue as opposed to a memory. The memory is still there.

BRIAN GOLDMAN: And, you know, there's an interesting thing here that we ourselves as individuals decide what's important and what isn't. And I say that because I'm thinking of President Joe Biden I'm sure remembering the details of the day his son Beau died but had trouble remembering the date. And that resonated with me because I have trouble even today remembering the date that my father died, in part because his death was shortly after the day changed. The date changed. It was 1:00 a.m. And I was sleep deprived because I'd worked in the emergency department the night before and because he'd been ill that day, the day that he died rather suddenly. I was up all day, so I'd been up for 42 hours when I slept for an hour, and then I found out that he had passed away. Well, when I tweeted that, I had a lot of people who said, oh, I remember all the details of the day, but I can't remember the date if my life depended on it. My question is, you know, the salience of the information that we're being asked to remember is individual, isn't it?

NATASHA RAJAH: Yes, it is. And there's different types of salience. So you have the external like perceptual salience sometimes is what draws our attention. And we will remember really vivid experiences because there's some perceptual event that's like really striking. Like say when we see a car crash on the side of the street, like we'll remember that because it's such a salient perceptual experience. But then there's also what we attribute salience to, right? So what from our internally motivated state do we pay attention to, do we actually perceive and encode in a deeper quality? And emotion, an emotional valence of a stimulus really enhances our encoding of that stimulus. So you will remember the emotional aspects of the day to a greater degree than the more mundane aspects of the day. But at the same time, the date is more of a semantic thing. It's whether you paid attention to that day and if that was relevant to the event at the time. So it's probably something that was not the focus of your attention and not something you really were paying attention to because you were going through all these other emotional experiences that were more salient and probably had more primary access to the encoding processes.

BRIAN GOLDMAN: We've started to talk about the brain, and I want to go into that in a bit more detail. There are many areas that are important too to memory and the brain, but the hippocampus is one and the prefrontal cortex is another. Can you talk about the physical structure of the brain and how those changes as we get older might affect our memories?

NATASHA RAJAH: So it's important to consider there's both healthy and what we consider normative ageing, and there's also pathologies of ageing. In our research on what we consider normative ageing, sometimes, we are detecting preclinical stages of these more pathological ageing profiles such as dementia and Alzheimer's type. But generally, what we see with healthy ageing is that we see reductions in the volume of the hippocampus, and we also see reductions in the volume of the prefrontal cortex. Now, when these reductions start and the rate of progression does differ, so prefrontal volume decline starts at the age of 30. And it's very gradual and it grows across the adult lifespan. Whereas the hippocampal volume decline really occurs in your mid to late 50s. And then depending on whether you're healthy or pathological, it could accelerate or show a steeper decline in more pathological states. So the hippocampus is really important for encoding declarative or memories that we are aware or consciously aware of. Whereas the prefrontal cortex, it's important for kind of the executive functions associated with memory encoding and retrieval. So we all apply strategies when we know we need to remember something. And the prefrontal cortex is really important for supporting strategic application at encoding, and then also giving you a strategy when you're trying to retrieve information when a cue is present. So when we see memory decline related to the prefrontal cortex, often, it's not a primary memory problem. It's almost that you have a problem with retrieval, a problem with searching or a problem with organizing information appropriately at encoding. Whereas when we see loss in the hippocampus, it is more of a problem with a mnemonic process. So you really have challenges in encoding. So this comes from neuropsychological studies of patients that have damage to these two areas of the brain. So individuals that have hippocampal damage have profound amnesia. So an inability to learn new information and retrieve information. In contrast, patients that have damage to the frontal lobes, they often can do memory tasks that have a lot of environmental support such as a recognition memory task. When you actually see a stimulus and are asked whether or not you remember seeing it, they could perform pretty well on that type of task. But when you ask them, you know, whether or not the stimulus they saw was on the left or the right side of a screen when they saw it, that type of more contextual detail that requires a bit more strategy to encode and retrieve seems to show a deficit. So this tells us that these two systems have a complementary role, and they play different roles in memory acquisition and in retrieval.

BRIAN GOLDMAN: What, if anything, are the differences between male and female brains as we age?

NATASHA RAJAH: There has been an assumption that there isn't a difference. And so when we see a memory decline with age, that the neural basis of that memory decline is similar in males and females. However, this is… I'm happy you asked this because this is an area that my lab is very active in. We conducted a study where we actually looked at whether or not the neural correlates of memory decline using functional magnetic resonance imaging were the same in males and females. And what we found was even though behaviourally, both males and females show the same pattern of memory decline in healthy ageing, the neural basis that that declined was very different. And with females, it seemed to be more associated with alterations in prefrontal and pridal activation. Whereas in males, we actually couldn't find a strong signal, but it seemed to be more in the more temporal regions of the brain. So it might be that there's different mechanisms underlying memory decline in healthy ageing in females versus males. So we don't know much. This is an area that's starting to be investigated. And the reason that we're really interested in this question is because there are sex differences in the prevalence rates of neurodegenerative disorders. So for example, two thirds of Alzheimer's disease patients are females, but more males consist of the Parkinson's. So there's more males in the Parkinson's disease category. So there's sex differences in these biologies. And so we're trying to figure out what might be happening in normal ageing in order to inform us about these more pathological states.

BRIAN GOLDMAN: That's a good segue into talking about the Cliff, as it were. There's been a lot of talk about memory and ageing, especially with Joe Biden and Donald Trump making very public memory gaffes. What are some of the specific and expected changes in memory capability that happen somewhere around the age of 80? I realize that you've already mentioned that maintainers may not go through this for a long time to come, but what are some of the changes somewhere around the age of 80 or thereabouts?

NATASHA RAJAH: So as I mentioned, like with healthy ageing, we often see a decline first in our ability to remember spatial context of where you parked your car, temporal context, you know, the order in which you were introduced to friends at a party, for example. That's pretty normal. And it starts at 40 and it continues into older age. As you advance into older age, so when we're talking about 80, you're considered an old, old adult in some ways. So you're older and then you start to see deficits in a recognition memory, the inability to remember who you saw at the party, bit more profound memory. You also have deficits in other types of cognitive functions that affect memory. So like I mentioned, the executive function. So you might be less likely to use an appropriate strategy to encode information, and so you have these memory failures that become more profound at 80. But it really isn't as though there is a sudden change at 80. There really is more of a subtle linear decline as we age. If you do have a sudden change, it might be indicative of something less normative.

BRIAN GOLDMAN: Forgetting information that maybe is extraneous or getting in the way or is helping you carry on with your life, it can actually be considered a good thing. Can you expand on that?

NATASHA RAJAH: You know, there are negative experiences that we all have in our day to day. And if we focus on them and we kind of get stuck on them, they actually can have a negative effect on our quality of life. So it is good to actively kind of suppress these negative experiences so they don't have as rich a representation in our mind and can hinder our future behaviour. Similarly, if you have perfect memory and you remember everything, you have difficulty sifting between what is relevant and important and you'll have more interference for your day to day. So memory loss and forgetting is actually a good thing because it makes space for new information to be encoded, and it actually lets memories that are less relevant to your survival and to your success to take up space. And so you could actually have more attention and more resources to acquire information that's relevant to your, you know, your day to day happiness and your day to day success.

BRIAN GOLDMAN: My mother and my sister both had dementia, so you know what I'm going to ask, and you've already deftly pivoted back and forth between what is pathological and what is just a normal part of ageing. But I want you to put it all in one place. What's the difference between naturally declining memory as we age versus a condition like dementia, either Alzheimer's dementia or perhaps dementia associated with Parkinson's?

NATASHA RAJAH: Dementia associated with these pathological states are much more profound, and they affect the activities of daily living. So what you can do day to day, it could result in profound effects, like if you take a car and you get lost while driving because you can't navigate your way back home. As opposed to not just remembering the details and kind of like the circumstance in which a past event occurred or what the focus of your attention was in the past, you actually start having difficulties in remembering items. So the actual recognition. The focus of your past experience might deteriorate with these more pathological states. In addition, you might have difficulties with other types of memory associated cognitive functions. So when you look at dementia, it's not just episodic memory that declines. You eventually do see some deterioration in semantic memory, memory for world knowledge, and you will also see declines in executive function. So the episodic memory might be one of the earliest signs of dementia. But with profound dementia, you really do get decline across many cognitive domains. So it won’t just be memory, it will be also some semantic information. There might also be some language difficulty and word finding difficulty. So it becomes more profound as the neural correlates of the brain that are affecting these memory systems and cognitive systems show more and more pathology. So it progresses with sort of these amyloid plaques and these nerve library tangles that we know are prevalent in, say, Alzheimer's disease. So where these pathologies arise in the brain will also affect the type of cognitive processes that are mediated by those brain systems.

BRIAN GOLDMAN: So why do some people of the same age have better memories than their peers? You've talked about maintainers. What's with maintainers?

NATASHA RAJAH: So there is quite a lot of evidence that maintainers do tend to have higher education, that higher education is protective and does provide some reserve. There's also they come from higher socioeconomic status, so they have had more privileges in life. They’ve had probably better diet. There's evidence of good vascular health. So exercising, keeping your belly weight off. All those things seem to support healthy ageing by reducing vascular burden with ageing. So there's a lot of things that maintainers have going for them compared to decliners, but some of the more noticeable ones is education and just general better vascular health.

BRIAN GOLDMAN: Are there general daily habits that can help us maintain our memories a little bit better than others?

NATASHA RAJAH: One of the things that some of my research has shown is that you could really help your memory by supporting your executive function. So not necessarily memory per se, but your ability to pay attention and really take in the information that you want to take in, applying a strategy when information is important to you. And so that kind of approach and just engaging your executive functions and your strategic abilities during memory encoding can really support memory, even if you're showing some age related memory decline. The other things you can do is really maintain your general physical health. So keeping your vascular health good, keeping the fat from your midsection off and being actively engaged. The other important thing is there's a lot of research emerging now about social isolation and its negative effects on cognition in older adults. So being socially engaged and having meaningful relationships also help maintain your cognitive function with ageing.

BRIAN GOLDMAN: Finally, you know, we're talking about the memories that people lose or their ability to either retain or their ability to retrieve information. There are good aspects to ageing when we think about things like experience and wisdom that comes from having seen events play out in different ways, maybe we understand something better because we lived through it 30 or 40 years ago. Can you speak to that?

NATASHA RAJAH: As I mentioned, like semantic memory and knowledge increases with age in general in healthy ageing. And this increase really does benefit the wisdom and the ability to older adults to draw from more experiences to infer what the right decision is. So when we think about when you talked about Joe Biden, you know, yes, there might be some memory gaffes, but he has experienced a lot, and he probably has a lot of wisdom as to how to make decisions or how to come to decision based on these experiences. In addition, there is some research showing that in general, overall, if you're not experiencing any health issues that could have a negative effect, in general, there's like a happy smile kind of shape to happiness across the lifespan, where in older age, older adults tend to be happier, probably because they can contextualize their experiences. And also, there's evidence that if you're in a healthy cognitive state, also regulate your emotions more positively and gain access to more positive experiences in life and focus on those. So there is some evidence that older adults tend to be happier because they've had the experience of going through negative events, and so they know how to focus on the positive and therefore, you know, benefit and maximize the positives in their day to day lives as well.

BRIAN GOLDMAN: And in the interests of political fairness, whatever you said about Joe Biden would probably also be true about Donald Trump.

NATASHA RAJAH: Yes.

BRIAN GOLDMAN: Natasha Rajah, I want to thank you so much for a wonderful conversation that I will not soon forget.

NATASHA RAJAH: Great. Thank you so much, Brian.

BRIAN GOLDMAN: Natasha Rajah is a full professor and tier one Canada Research Chair in Sex, Gender and Diversity in Brain Health, Memory and Ageing in the Department of Psychology at Toronto Metropolitan University. Here's your dose of smart advice. As we get older, it's not unusual to notice that you don't remember information as well and aren't able to recall or retrieve it as quickly. As we age, the type of memory that takes a hit is called episodic memory. Things like where you put your keys, where you parked your car and remembering the names of people you've met recently. These lapses are due to changes in structure and in function of two parts of the brain called the hippocampus and the prefrontal cortex. You may not have noticed it yet, but research shows that episodic memory, especially contextual details, begins to decline in early midlife. For instance, you remember a birthday. You remember the person, but you may not remember who sat next to you at the dinner celebration or what they were wearing. Memory often declines markedly with age. Some researchers think it's because we lose the ability to pay attention to details that would help us remember. Some think it's because our brains lose the ability to store memories. Others believe the memories are there, but we lose the ability to retrieve them quickly. Age related memory problems like forgetting your keys are not symptoms of dementia, where you not only lose the ability to recall the context around a thing, but the thing itself. For example, not remembering what you did this morning or who you spoke to this morning. Fortunately, there are many things you can do to strengthen your memory, like take care of your body, diet, regular exercise, taking medications as prescribed for diabetes and hypertension. These can make a huge difference. Often, you don't remember something because you didn't put enough effort into trying to remember it. To build context, focus on helpful little details surrounding what you're trying to remember. Reinforcing habits help. You remember better where you put things if you put them in the same place every day. Get into the habit of carrying a notebook or tablet to record what you want to remember. As you get older, you can use that device to help you remember things like appointments and organize your life. In that way, technology can help support your memory. So can your partner, your kids, your friends and co-workers. Use them. That's what smart older leaders do. They recruit a team. Use their wisdom and experience to set the right course, and let the team help out with the details. If you have topics you'd like discussed or questions answered, or if I've forgotten something, our email address is thedose@cbc.ca. If you liked this episode, please give us a rating and review wherever you listen. This edition of The Dose was produced by Sameer Chhabra. Our senior producer is Colleen Ross. The Dose wants you to be better informed about your health. If you're looking for medical advice, see your health care provider. I'm Dr. Brian Goldman. Until your next dose.

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What happens to my memory as I age? - Transcript

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