Associate Professor Michael Valenzuela
When researchers talk about social engagement, they’re really talking about getting out of the house, and trying to measure that, getting out of the house to meet either your friends, family or new people. There are different ways technically to measure that. Sometimes it’s literally, “How often are you meeting or getting together with a friend or a family member?” You can get a little bit more complicated and actually try and map out people’s social networks, but the general idea is meeting people that you either know or new people, and outside of the house.
There’s now quite a lot, dozens, of population-based studies or public health studies, which really means you’ve got a large group of people who’ve been followed for a number of years, and that kind of research shows, time and again, that those who are more socially active have a lower risk of dementia. Or the inverse, if you’re socially isolated, then you have a higher risk for dementia. So, from that population-based research, I think there’s quite a lot of evidence for that. It becomes a little bit more difficult when we try and translate that to the clinical trials or interventions context, but I think the main message there is that social activity, social engagement, is a risk or a protective factor for dementia. I think that evidence is pretty strong. Moving from there, it gets quite complicated.
Why social engagement should be related to dementia risk is a really tricky question to answer. We’ve got lots of theories. If you just think about it in first principles, socialising with other people demands a lot of your brain. You need to work memory; a nice social interaction means, if you’ve met the person before, you remember something about them that you can incorporate in your conversation. You’ve got to plan ahead. You have to follow the niceties of social conventions, sometimes called EQ or emotional intelligence. It requires quite a lot of mental work. So the connection could be through cognitive exercise or cognitive demands. The other side of the equation is social activity, for most people, there’s an inherent reward feedback system there. It’s a pleasurable act, to go out and socialise, so that leads to more sustainable behaviour. So, once you start socialising, you get in the habit, you enjoy it and you do it more and more in your life. So there could be an emotional or emotive side to that link. Whether there is an inherent value to social activity and dementia risk, independent of either cognitive activity or the reward feedback, we don’t really know.
I guess on the negative side of social activity, if you’re withdrawn, you’re stuck in your house most of the time, not meeting your friends or family or not meeting new people, this is related to increased risk of dementia. And there are various sides to that observation. On the one hand, we do know that, in the years leading up to a dementia diagnosis, people start to withdraw somewhat from their social contacts, so it could actually be an early warning sign that maybe dementia is in the future for an individual. Or that person may be suffering from mental health problems, like depression, which means that you withdraw from your normal day-to-day activities and this leads to social withdrawal as well. So they could be two explanations for that observation, but I think there’s enough evidence from the public health literature, which tries to statistically adjust for those possible scenarios, and there is still a link between greater social activity being linked to reduced dementia risk. So I think there is some truth on both ends of the spectrum, that low social engagement is a risk factor for dementia, and high social engagement is a protective factor.
Unfortunately, I don’t think we can quantify what is the perfect amount of social activity. Putting a lot of different streams of research together in my book, which is called “Maintain Your Brain,” I really recommend a common sense approach to it, which is that, particularly after retirement, because a lot of things change in retirement - one of the more stark things is that people go from a social network at work to often having a much more restricted social network, so I think it’s really important after retirement that people try and replace that social engagement. And what that means, I think, in terms of recommendations, is that people should try and start some new pastime or hobby, or join some kind of interest group out there, which means they’ve got to leave the home, they’re meeting new people. Ideally it’s ticking off what I call the three keys: that it entails or has cognitive activity, social activity and some physical activity. If you can try and start a new pastime that has those three key ingredients, I think you’re doing a good thing to lower your risk for dementia.
不幸的是，我不认为我们可以量化什么是完美的社会活动量。在我这本名为“保持你的大脑”的书里，我把大量不同的研究结果放在一起，从而推荐一种特别是在退休后使用的一种常识性的方法。因为在退休后许多事情发生改变 – 其中更严峻的事情是人们在工作中的社交网络经常有一个更受限制的社交网络，所以我认为在退休后，人们试着换一种社交参与方式是非常重要的。我认为应该建议人们开始尝试一些新的消遣或爱好，或加入在那里的某种兴趣小组，这意味着他们必须离开家，去认识新朋友。理想情况下，它敲出了我所说的三个键：它需要或具有认知活动，社交活动和一些体育活动。如果你可以尝试和开始一个有这三个关键因素的新的消遣活动，我认为你在做一件降低你患认知症的风险的好事情。
Text Overview of Video
Professor Nicola Lautenschlager
It is important to discriminate, when we use the term “depression,” between the term how we use it often in everyday life, “Oh I feel depressed today,” and depression as a medical condition. In the latter scenario, depression is a mental health problem, and is an illness and, obviously, is a very important illness to treat, because if not recognised and treated, it can come along with very severe health outcomes. It is one of the most common mental health conditions, and it is actually also one of the most common health conditions, full stop. Current estimations of how common depression is globally, estimate that roughly, at any given time, 350 million people suffer from depression globally. When it comes to using depression as a term in our everyday language, we often describe with that [word] just having a bad day, and sometimes it can also mean feeling stressed. We all can have symptoms of depression. Let’s say we go through a very difficult phase in our life. We have adverse life circumstances, without actually fulfilling the criteria to experience full-blown depression as a medical condition. What are the essential criteria or essential symptoms of depression as an illness? Obviously, most important is the symptom of feeling down or having a low mood. That’s usually considered central in a depressive episode, for example, but it has to be more than that. Usually it has to be around for a certain duration of weeks. It has to be severe enough that it impacts on the person’s daily life. For example, it impacts on their work or impacts on their family life. There are other important symptoms like having poor sleep, or having changed appetite, having changed energy levels, and the interesting thing about depression is that it can go either way. You have people who are more fatigued and sleep more, and have no energy, and find it very difficult to get out of bed and do things. But then you can also have people who have more an agitated depression, meaning they’re restless, they can’t sleep, they are overactive, they’re reactive, but all the activities they might do might not be very meaningful, because they can’t concentrate.
The challenge with depression is that it can come with various forms of presentation, and therefore can be missed, for example, in general practice, especially if it presents in an unusual form. One interesting question is, “Does depression look different in a younger person versus an older person?” What’s important to understand is that the core symptoms of depression are the same in young and old. But research tells us that in old age there are certain symptoms which are more prominent, when it comes to depression, than in younger people. I’ll give you an example. Older people with depression tend to feel more somatic symptoms and these are usually the complaints or the concerns they communicate to their general practitioner. So they have headaches or they have problems with their stomach or their bowels. They might have pain in their chest or they feel they have weak muscles. So we have to be mindful, working in the health field, or also just as family members, that when an older person has many changing and various health complaints, somatic health complaints, that what could be behind it is a depression, especially if the general practitioner investigating can’t find any causes for these complaints. That’s different to younger people. Since younger people tend to experience more the mental health side of depression, with having a low mood and feeling irritable, for example.
Another important fact to be aware of, is that older generations of people tend to associate a bigger stigma with having a mental health condition such as depression, and therefore are much more reluctant to talk about it, because they often interpret that as a failure of who they are, and it might be a sign of weakness, or weakness of character. It is rarer in older people for them to talk about their mental health, even to their loved ones, than on average it is in younger people. There is also an interesting gender bias. So, not surprisingly, looking at western societies, men find it harder to talk about their mental health than women, and there is also a geographical difference, that people living in rural communities find it harder to talk about their mental health compared to people living in cities.
One important point when it comes to depression in older people is, to try to investigate “Why is the person experiencing depression in the first place?” This is particularly important if it is an older person who never had a depressive episode before in their life. We call that having late onset depression for the first time in their life. The reason why this is important is, that there are different health or medical conditions which might be causing the symptoms of depression. It could be just a depressive episode for various reasons, and these reasons could be changing of the body, physiologically, due to ageing, additionally with chronic health issues, additionally through changes to their life circumstances, but it also could be a symptom of emerging biological changes to the brain, due to cognitive decline or emerging dementia. We do know that there is a certain percentage of people who develop, later on, dementia, such as Alzheimer's disease, where the first symptom was actually change to their mood with developing depression, and research has shown that can be several years before there is any onset of clear cognitive changes.
It is important not to scare people who have late onset depression, because that might not be the case for them. What the recommendation is for clinicians is, if a person develops late onset depression, to assess their memory, and even after they have recovered from the depression, to see them on a regular basis and to continue to assess their memory, just to have an eye on it. Because usually, if it would be due to underlying dementia processes, eventually you would be able to measure the cognitive decline. To give you an idea, most studies statistically estimate that a person with late onset depression has roughly a twofold risk of developing cognitive decline, compared to an older person who doesn’t experience late onset depression.
How common is that, that an older person with depression also has problems with their cognition? Studies estimate between 40% to 60% of older people who experience depression have, at the same time, problems with their cognition. Very often it is around being able to concentrate and pay attention, which is typical for depression, but this is a much higher percentage than in younger people. Sometimes one comes across a term called “pseudo dementia” especially in the older literature which tries to describe these changes to cognition, while depression is present, and it’s called “pseudo” because very often when the person has recovered from their depressive symptoms, also their cognition returns to normal again.
Text Overview of Video
Professor Nicola Lautenschlager
When we look at common risk factors for cognitive decline and dementia, depression is one of the most prominent ones. One interesting question is, “Why is that the case?” and, “What do we know about this?” One observation is that, especially if people have had several significant episodes of clinical depression throughout their lifetime, that it looks like there is an accumulative risk of depression, in terms of their cognitive health, when they get older. There are some underlying strong hypotheses, which one comes across in the literature, about why increasing numbers of depressive episodes throughout life might increase the risk of dementia later on. One of these hypotheses is that it has to do with the impact of having increased stress hormones in your body, while you go through a depressive episode. For example, one of these stress hormones is cortisol, and we do know that if you have, for a prolonged period, high levels of cortisol in your body, as is the case when you have a depression, it specifically damages the neurons in the hippocampus, which we know we need to lay down new memory, and which is the area which is damaged early in Alzheimer's disease. Therefore, the message for consumers and clinicians is, if depression is present at any time in life, it’s important to diagnose it as early as possible, and to treat it effectively, as early as possible, to reduce the time with having high hormonal stress burden on the brain. It is more the untreated, unrecognised depression which is harmful for future dementia risk, and not so much the well treated depression, if that makes sense.
Another interesting fact is that depression and dementia share many risk factors, and they’re both common. Obviously, an interesting research question is, “How much are they connected, and how much is just the fact that they share common risk factors?” I’ll give you an example. It has been shown that early experience of trauma in childhood, which might be physical, sexual or psychological, is harmful for having a higher risk later on of developing depression. But more recently, it has also been shown that it is a risk factor independently for having a high risk of dementia. That’s just one example. If you look at chronic health conditions, we know that especially cerebrovascular disease or vascular risk factors, like chronic heart disease, chronic hypertension, anything which basically damages the blood vessels and subsequently also the blood vessels in the brain, increases the risk of having depression, but also increases the risk of having cognitive decline. There is actually a specific term for older people, when they experience depression in the presence of many vascular risk factors, which we call “vascular depression.”
When it comes to treatment of depression in older people, the take-home message is, it should be treated as aggressively in older people as it is treated in younger people. There is no room for therapeutic nihilism just because a person is older. The good news is that older people very often respond very well to appropriate treatment which, for most people, would be a combination of social support and psychological support, plus use of anti-depressants, and usually general practice is the area where this treatment takes place. Basically, depression is one of the best treatable mental health conditions we have. There are some differences between young and older people. Because of the presence of chronic health problems, there is a percentage of older people with depression who have a poorer outcome in terms of recovery. Meaning they might have more, what we call, treatment resistant depression, or might not be able to be completely free of symptoms. They also can have a higher risk of relapse. So the recommendation is, if they benefited well from an anti-depressant, they should stay on that medication and not stop again, to avoid the higher relapse risk.
A common myth is that older people are less able to benefit from psychotherapy. This goes all the way back to Sigmund Freud, who stated that himself, that if a person is older than 50 years they are too old and rigid to benefit from psychotherapy. It’s quite amusing because when he got older himself and was in his eighties, he actually reversed this statement and said it’s not true, but by that stage people were not listening to it anymore. So older people should be offered psychotherapy, if appropriate. And it has been shown, in research studies, that people who are psychologically-minded benefit very well from, for example, cognitive behavioural therapy, even if they’re older. What is a challenge in the health system in Australia, is that very often, there is a lack of therapists who are specialising in older people with mental health problems.
One important message is that older people with depression should receive adequate treatment and there are regular mistakes happening in this field. One common mistake is that healthcare providers give a too low dose of an anti-depressant, for example, because they are anxious it could have negative side effects. On one hand, obviously it’s important to be careful and older people often do need lower doses, but we see in clinical practice that very often the dosage is not increased to an adequate level, or not given long enough, and then often it’s wrongly concluded that the medication is not working. It’s really important to treat long enough, with the right medication, at the right dosage. This is also important because the longer the older person lives with clinically relevant depression, the more it increases the risk that their cognition is impacted negatively and it increases their risk of dementia.
Another important aspect is how our society thinks about ageing. An argument you hear quite often, for example, from nursing homes is, “Oh yes, if I lived like this person, I would be depressed as well.” So it’s normal for this person to be depressed, so we don’t need to treat it. As a society we need to work on that we all change these attitudes, and say an older person is as much entitled to the best possible healthcare as a younger person, and that this is really a sign of ageism, if we conclude, as younger people, that it’s not worth the effort, or that it’s normal for an older person to suffer.
Depression as a symptom is one of the most common non-cognitive symptoms of dementia. People who have dementia, for whatever cause or reason, have a much higher risk of experiencing symptoms of depression than an older person who does not have dementia. Screening for, and detecting, depression in patients who experience dementia, is very important as, again, it has very poor outcomes for them, if the depression is not recognised. There are quite interesting studies that report very high numbers of depression in, for example, residential care.
Interestingly, when it comes to treatment of depression in people with dementia, more recent research has shown that, unfortunately, the currently available anti-depressant medication is less effective, for example, in people with Alzheimer's disease and, furthermore, that people with dementia often have a higher risk of experiencing negative side effects of the medication. It is important to take that into account when a treatment plan is put together. However, the current recommendation is still, if a person is significantly depressed with dementia, medical treatment with an anti-depressant should be considered. If the depression is rather of a milder nature, then the recommendation is maybe not to use anti-depressants as a first line treatment, but rather try non-pharmacological approaches. So that could mean increasing pleasant activities, making sure the person’s not isolated, increasing social contact, increasing physical activity, nutrition and diet and all these things, and see if that already makes a good impact.
A rather new, but very important field of research, is investigating what we can do to prevent the onset of depression in the first place. So if we could think of a health care system where we reduce, from the outset, the risk for an older person to experience late-onset depression, that would be perfect. The knowledge in this area is still very limited. Again, there is some interesting research highlighting that prevention of depression might be possible, and factors to think about and look at more closely are the social environment of an older person, trying to avoid that the person is isolated or feels disconnected from their community, feels they’re a burden, or can’t actively contribute any more to society, would be important. But equally, to look at their physical health, to manage optimally chronic disease, as it is a strong risk factor for depression. Other areas are, for example, hearing loss and loss of vision, which both are strong risk factors for depression in older people, to screen for that regularly. So it looks like there are quite a number of things we can do as a society to reduce, in general, the onset of depression, and that subsequently obviously also help to reduce the onset of cognitive impairment and dementia.
Prof. Carol Brayne
What are the detailed effects of education? I think that is a very challenging question, because it could be argued that a poor education or low access to education, is itself a risk factor, and that maybe high education is separately a protective factor, and an average education is maybe the neutral state. I would argue that we probably don’t really know the answer to that question. There is the opportunity across the world to examine it because there are many populations in which access to education is very limited. And, of course, we’re talking about findings from a country in which education has been the norm for a long time. So we’re looking at variations in education, rather than no access, or absolutely minimal access. So I think we’ll understand a lot more about education in the years to come.
So the EClipSE Study is a grouping of three population based studies of dementia. One is of the 65 plus population; one is of the 75 plus population and one is of the 85 plus population and there are two in the UK and one in Finland. These studies have all studied dementia in the population. But what makes them stand out, is that they’ve also had a brain donation program associated with them. So in that research, we have gone out and asked people whether they were willing to consider donating their brains to medical research after they died, and their families as well, so we talk with their families. Between them those studies have collected a thousand donations. The reason why we brought them together was because, individually, each study is not powerful enough to look at the relationship between what you see in the brain and what you’ve measured during life, taking into account the various different factors. So we wanted to have the ability to look at what might be protective factors and compensatory factors in people’s lives that influence how they might or might not have had dementia.
In that study we explored the hypothesis that education is associated with less dementia. Now that’s a question that’s been addressed many times in ordinary cohort studies, in ordinary longitudinal studies, and we know that education is protective of later development of dementia, from a whole range of studies. What we wanted to do with this study was see what was the brain mechanism for that. And what we found was that if you have a certain amount of the changes associated with dementia in your brain, and if you have high education compared to low education, that the people in the high education group have less dementia during life. So just rephrasing that, if you hold the amount of neuropathology steady in a brain, whether you have more education or not influences whether you develop dementia during life or not. So that tells us that there are other things going on in the brain which allow us not to express dementia during life, even if we have say Alzheimer’s or vascular changes in our brain.
What we looked at was the dose of education and the dose of education seemed to be important. Not just the availability of education, so it’s not just confounded by other things. But it seems almost certain that there are a variety of ways in which the measure of education could be associated with protection from expression of dementia. So it could be having a bigger brain at the beginning. It could be higher IQ because there’s an association between those two. It could be higher access to educational exposure. And then it can be the things that a higher education then is associated with in later life. Because we also know that more intellectually stimulating occupations and later life engagement, also have a protective effect, and each of those, they’re associated with each other, but we know they also have independent effects.
Difference between pathology and dementia
Dr David Ward
When we talk about the developments of dementia, there are two distinct events that are worth mentioning. The first is the development of the disease. So in the case of Alzheimer's that's the amyloid plaques and the neurofibrillary tangles, and these can cause some detrimental effects such as atrophy or shrinkage to the brain. Now the other event that occurs, is obviously the onset of dementia, so that's the cognitive impairment, and the deficits in memory and attention that are associated with Alzheimer's disease.
Interestingly we know that there isn't a direct relationship between the level of damage in someone's brain and their cognitive function. For instance, some people can have quite a high load of damage, a large presence of Alzheimer's pathology, yet they're still functioning normally, and they aren't suffering from any of these detrimental memory deficits.
Other people can have just a small level of damage to their brain, yet they start showing these deficits on a day-to-day basis, and they have more difficulty with memory function and planning. We aren't exactly sure why some people seem to be more resilient to Alzheimer's, while other people seem to be more susceptible to its effects, but one of the factors that may partially account for some of these individual differences in when dementia symptoms begin to emerge, is cognitive reserve.
Introduction to cognitive reserve
Dr David Ward
What we see is that the level of protection that someone has from the emergence of dementia is related to their cognitive reserve, and cognitive reserve seems to be built from a lifetime of exposure to cognitive stimulation. Simply put, if you live a life that is more cognitively engaged and you're more involved with these complex learning activities, then, on average, you'll have a lower risk for dementia later in life. For example, we might have two individuals, person A, and person B, and they both have exactly the same level of damage within their brain as a result of Alzheimer's disease. However, person A has greater cognitive reserve, and what that means is that they don't display any of these deficits, any of these dementia symptoms, and they're going about their business fairly normally. Person B however, they have less cognitive reserve, and although they only have the same level of damage as person A, what we see is that they might start showing some of these day-to-day difficulties in memory and attention, some of the earlier symptoms of Alzheimer's disease.
However, something worth mentioning is that cognitive reserve is a theoretical construct. Now a theoretical construct is something that we believe to exist, because it explains a number of associations, but we can't directly measure it or observe it. In the case of cognitive reserve, it provides a great explanation for why people with more years of education have a lower risk of dementia, but we can't directly measure it. We can't go into someone's brain and look at a specific structure that seems to expand when they're exposed to more years of education. Despite this, we do have a few ideas as to how cognitive reserve does look in the brain, and we can start to differentiate between brains that have high cognitive reserve and low cognitive reserve, based on their structure and function.
What cognitive reserve looks like in the brain
Dr David Ward
What we think happens, is when a brain is exposed to this prolonged engagement in challenging cognitive stimulation, this induces changes to the structure and the function of the brain, to make it more resilient and more flexible. There are two main components here at work. The first is neural resilience. Neural resilience refers to differences in the efficiency of the neural networks within a brain. Neural flexibility, on the other hand, refers to differences in the ability to recruit additional neural networks to process a task, when the original network is disrupted by pathology. A neural network is a collection of neurons and synapses within the brain that work together to help process a task. So, in one case it might be if you enter a supermarket and you forgot your shopping list, there might be a number of networks involved with trying to remember those items. If there is damage to these networks, or they can't function normally, then that's when you start to have difficulties remembering, and with other cognitive processes.
Neural resilience and flexibility
Dr David Ward
To better understand how these differences in neural resilience and neural flexibility may actually operate, a nice metaphor may be to use a delivery van driving along city streets. In this metaphor, the delivery van represents a neural impulse that's travelling across the brain to help process one of those tasks, such as remembering the items on the shopping list, and the city streets represents the neural networks within your brain, and the pathways. If you have high cognitive reserve, then you have greater neural resilience and greater efficiency within your neural networks. When the delivery van is driving along a street and it wants to make a delivery at the other side of town, if it's driving along a nice high quality street, then it's not going to face any difficulties at all. Even if a bit of damage starts to occur to this road, because of its pre-existing high quality, quite a large amount of damage needs to occur before that delivery van starts to have difficulties in actually making its delivery, and a very high amount of damage needs to occur before it can't make its delivery.
However, if you compare that to an individual with low cognitive reserve and low neural resilience, then the delivery van is driving along a road that's already pretty poor quality. There might be a few potholes and it's pretty clear that the council's been neglecting it over the last few years. The delivery van can still make its delivery, but if any further damage occurs to that road, then it's probably going to be un-driveable pretty quickly. Neural resilience refers to the differences in the quality of the pathways, the differences in the quality of the neural networks and their efficiency, whereas neural flexibility refers to the differences in the ability to recruit additional roads to make your delivery if necessary. So let's go back to the delivery van, and what we might see is that the van is driving along, and so much damage has occurred to that road that it can no longer pass and it's making its delivery more difficult. If someone has high neural flexibility, they'll be able to back up the van and they'll be able to think, “Well, if I take a left here, and then I take a right, then I'll still get to my destination, even though I'm not travelling along the road I'm intending to travel along.” We compare that to someone with lower neural flexibility, and what we might see is the van backs up, but because there aren't so many options within the street, the van has no way to get to its destination other than travelling along that damaged road, which it can't do. To sum up, neural resilience refers to the differences in the quality of the roads, whereas neural flexibility refers to the differences in the number of options.
How can you increase your cognitive reserve?
Dr David Ward
The question of how can we increase our cognitive reserve is really important. If there were a way to lower your risk of dementia, and many people in the world, or just in Australia, undertook that activity, then we would have a much lower prevalence of dementia. Typically, if an individual wants to increase their cognitive reserve, the best activities are those activities that involve prolonged engagement with cognitively challenging activities, that preferably involve new learning, learning of new knowledge or skills.
A great example of an activity that involves prolonged engagement in a cognitively challenging task, is learning a second language. When you learn a second language you're taking in new vocabulary, you're learning how to structure your sentences properly, and it takes quite a long time. It's quite difficult, but it's also achievable, and that's a really key point. There's no point throwing yourself into a task that is so difficult that you can't actually see yourself getting better at it.
As a result of this activity, your brain has to change, it has to restructure and reorganise itself, and that's what we think increase in cognitive reserve looks like in a brain. Although it's helpful to give a few examples of certain activities that might be good for increasing cognitive reserve, typically in the research and in the literature, we talk about more broad categories of lifetime exposures. What we find is that people who have more years of education have a lower risk of dementia later in life. It's not just limited to education however, and people who are involved in occupations that involve more complexity, with people or things, have a lower risk of dementia as well. A great example of these occupations are those positions that involve management of people, because that's a difficult and challenging thing to accomplish. An individual's engagement in cognitively stimulating leisure activities also seems to be associated with a reduced risk of dementia. We think that people who read more books or visit museums more regularly have a higher cognitive reserve than those who do these activities less frequently. The take home message, however, if you want to increase your cognitive reserve, is that you need to be challenging yourself with new learning on a regular basis.
Brain reserve vs. cognitive reserve
Dr David Ward
To make things a bit more complicated, you can split this up, these protective effects, into cognitive reserve and brain reserve, and that's quite a useful distinction to make. To understand the differences between cognitive reserve and brain reserve better, we can use a hardware and software metaphor. Brain reserve refers to the hardware, so it's what you have in your brain. It's how big your brain is, it's how many neurons you have, and it's how many synapses you have, among other things. Interestingly, if you have a larger head circumference, that is associated with a reduced risk of dementia. It's quite a crude measure, but what we think happens there is that the more brain you have, the more brain you have to lose, before you start showing some of these clinical deficits associated with Alzheimer's disease. Cognitive reserve, on the other hand, refers to the more software side of things, so that refers to the differences in how you use what you have. As discussed, there are differences in neural efficiency and neural flexibility, and these can lead to a brain that's big that's not very efficient, or it can lead to a brain that's small that's very efficient.
Associate Professor Michael Valenzuela
Cognitive lifestyle is a concept that I’ve been interested in for a while now, which is really trying to think about the patterns of usage of your brain over your whole lifespan. What do you typically do with your brain? Are you someone who is always trying to find new information, learn new things, or are you quite happy not to learn new things, and just stay with the status quo? So I guess that’s the general concept, and we’ve done quite a bit of work trying to - being able to measure cognitive lifestyle in a more formal way.
Cognitive lifestyle, more and more research is showing, has a link to dementia risk in a similar way to when we’ve been considering social activity. People with, what I call, a poor or an unstimulated cognitive lifestyle, have high risk for dementia, and those individuals who have a very rich cognitive lifestyle, have a lower risk for dementia. Some years ago now, when we put this research together, we found that people with a very active or enriched cognitive lifestyle were about half the risk of dementia compared to an unenriched or low cognitive lifestyle. So that’s quite a big difference. And that’s true now, I’ve been shown in dozens of population health studies from around the world.
So when we talk about cognitive lifestyle, we talk about the lifespan. So some of that gets set up in young adulthood, particularly through education. Then, in the mid-life years, a lot of our cognitive lifestyle is related to the type of occupation we may be involved with, and then, in later life, particularly after retirement, it’s about those voluntary activities, where we’re getting out there and learning new things, meeting new people, and just doing things for interest that work our brain. So it depends what phase of life we’re talking about. If we’re talking about later life, then it’s really about the frequency of learning new material that challenges your mind, and also how challenging that is. Whether it’s just doing a crossword, which may be minimal, to learning a new language, which could be quite challenging.
The kind of research linking cognitive lifestyle to dementia breaks down in a few different ways. There’s been a lot of work in population health or the public health area, where you’re tracking, say, thousands of people for a number of years, and seeing who does develop dementia versus who doesn’t, and trying to work out what may be a risk factor or a protective factor. Time and again, it’s been shown that a more rich cognitive lifestyle is linked to lower dementia risk. More lately, my group and others have become quite interested in the idea of, well, if you’re presented with someone, an older person for example, what they’ve done early in life that’s fixed, what can they do going forward to enrich their cognitive lifestyle? And we’ve become very interested in brain training, or using cognitive exercises on the computer, as a kind of very formalised and encapsulated way of stimulating a cognitive lifestyle. So thinking of the brain like a muscle, brain training is like going to the gym and doing exercises for the brain.
We can’t get too prescriptive about what type of cognitive lifestyle is best for an individual, because there’ll always be a wide diversity of things. We may recommend one thing but, if the person doesn’t enjoy it, they won’t be able to sustain it for the rest of their life. So I think it really comes down to personal choice. Some people may be more attracted to kind of complex lifestyle activities. For example, like dancing, which may have a cognitive component, a physical component and a social component, and so that’s a kind of holistic cognitive lifestyle intervention. On the other hand, cognitive or brain training is quite specific, and is really trying to target specific cognitive skills in a repetitive way. I don’t think there’s any particular magic cognitive lifestyle activity to recommend. Rather, we have to do a lot of research and try and work out what are the strengths and weaknesses of all of those.
We developed a “lifetime of experiences” questionnaire because, at the time, there wasn’t really a good tool or assessment option to try and quantify someone’s cognitive lifestyle, whether they had a kind of impoverished or low cognitive lifestyle, intermediate, or quite enriched or high cognitive lifestyle. We developed this questionnaire which is intended to be filled out or carried out by an older person after retirement. Part of it we’re talking about, or asking them to reflect on what they did in the past as a young adult, in terms of education, during their working life, all the different occupations they participated in, and then there’s a very large section of the lifetime of experiences questionnaire where we try and really work out - what is the person doing now to stimulate the brain? What kind of activities are they participating in, how diverse they are, and how challenging they are. At the end of the day, we’re trying to put a number on cognitive lifestyle and then, through large studies, being able to determine a kind of bell curve for cognitive lifestyle, so that we could give someone like a percentile on this assessment tool.
So the lifetime of experiences questionnaire is broken up into phases of life. So we have early or young adulthood, where most of the questions are about education. How far did they get through the educational system? Then there’s mid-life, where a lot of the questions are about the different occupations they participated in. Not just the titles or the status, but also how many people were they in charge of? - what we call managerial experience. And then, for late life, which is I guess right now, what is the person doing with their brain now? What numbers of activities, diversity of activities, and how challenging those are.
所以我们可以将经验问卷的生命周期分成几个生命阶段。因此我们有早期或年轻的成年期，其中大部分问题是关于教育。他们通过教育系统有多远？然后有中年的生活，很多问题是关于他们从事的不同职业，不只是头衔或地位，还有他们负责多少人？ - 我们称之为管理经验。然后，对于晚年生活，这是我现在猜想，现在的人在做什么与他们的大脑有关的活动？什么数量的活动，活动的多样性如何，以及这些活动具有多大的挑战性。
In terms of which activities may be more important for lowering your risk for dementia, using our lifetime of experiences questionnaire, we don’t have that information yet, but I think that will be coming in the future, because, to answer that question, you really need data from thousands of individuals, tracked for many years, in order to know which activities specifically are protective or increase your risk for dementia. So we’re doing that right now in terms of pooling data from Australia, from France, from the UK, from the USA, so we have, at the end of the day, a really large sample and can drill down to specific activities. So it’s a great question, but we just don’t know the answer just yet.
Is it ever too late to start engaging in activities and thinking about your brain as a muscle? I don’t think so. I think more and more evidence, particularly clinical trials evidence, is showing that starting new challenging activities for your mind, such as brain training or complex leisure activities, is linked to better brain health, better cognitive outcomes. Whether that actually leads to lowering the incidence of dementia or the development of dementia, that’s still an open question, but we do know that it improves cognitive function and, in some cases, leads to better brain outcomes. So I think it’s never too late to think of your brain as a muscle and start new exercises for it.