Associate Professor Mathew Summers
There is anecdotal evidence, and some research, suggesting that in older adults, exposure to a general anaesthetic may result in activation of cognitive decline and dementia, post-surgery. That’s become an increasing area of interest. The hypothesis is that something is happening during the general anaesthetic, either the chemical or the process of anaesthesia, that’s changing brain chemistry or function, and that’s triggering a development of a dementia, following the exposure to general anaesthetic.
At this stage, the recommendation to avoid general anaesthetic for risk of dementia is not founded. There’s not sufficient evidence to suggest that. There are large scale studies that have shown an increased risk of dementia following general anaesthetic. There’s an equivalent large scale study that found no increased risk of dementia following a general anaesthetic, and there’s a third large study that showed decreased risk of dementia following a general anaesthetic. So again, the research is all over the place. We don’t have very clear randomised control trial evidence in humans that general anaesthetic is negative. The research is based on retrospective correlational studies.
The way we can look at why anaesthesia is being linked as a concern for dementia, comes down to the notion of causality. The research that we have is retrospective, in that we look at people who have developed dementia and we see that there’s a higher rate of those people who have dementia who may have had general anaesthetic in the last five to ten years, than the same age that don’t have general anaesthetic. The difficulty with such retrospective correlational studies is they don’t demonstrate causation. They demonstrate coincidences, two things that happened at the same time. The way that we need to go forward is with much better research, to identify what the underlying mechanisms are. And there are a range of possible explanations. Even if we do find that general anaesthetic has a higher rate of dementia in older people, it still doesn’t mean that anaesthetic is the causal mechanism. The person needed surgery for a reason. They may have had another condition that increases their risk for dementia, independent of general anaesthetic. During the process of general anaesthetic there are changes in brain chemistry and brain function and brain activation. That may be the cause. There are secondary complications that happen because of the medical condition that they suffered from that may cause that. They may have already had dementia, and the reason that we notice when they’re in hospital that they have dementia, is because in the community, with early stage dementia, with all their routines and structures around them, no-one noticed. And it’s when we put that person in an unfamiliar environment such as a hospital, with lots of supervision and monitoring, that people are starting to notice that person’s cognitive functions aren’t quite as sharp as they should be. And medical practitioners start to take notice that their memory’s not working too well, and assessment happens and they’re discovered to have dementia. But that has nothing to do with a general anaesthetic. They always had those symptoms, they just weren’t noticed. So we just don’t know where in that puzzle the anaesthetic comes in.
Associate Professor Mathew Summers
The relationship between a head injury and dementia is that people who sustain significant brain injuries in early adulthood, do show a slight increase in the risk for dementia in late adulthood. That link is because head injury results in pathological changes in the brain, both at the microscopic level in terms of changes to your neural connections throughout different parts of the brain, but also at the macroscopic level where we see large infarcts and areas of dead tissue.
The evidence again for the relationship between head injury and dementia is retrospective, not prospective, and there are ethical reasons why we can’t do a prospective randomised control trial and deliberately give a group of people a head injury and then see what happens to them. The only studies we can really do in humans, are looking at people who have sustained a head injury, and see whether or not they develop dementia. The difficulty we have is that if we look at the epidemiological evidence for head injuries, people at highest risks for a head injury are male, educated less than year 12, under the age of 25 at the time of injury, have low socioeconomic status to start with, and then subsequent to the head injury, will have educational and socioeconomic disadvantage. Those factors alone may account for why there is an increased risk of dementia in that cohort, because it’s difficult to compare that group of people then with a wider population, where we have 50% female and the education standards are different.
There is a new group of traumatic brain injuries that we are exploring in our research, that’s starting to appear in the research literature, and that’s related to sports related concussions, and particularly the risk of repetitive concussive injuries in contact sports. For instance, the sort of things we’re seeing out of the US relate to the NFL, the American Football League, where there are lots of concussive head injuries, which do not involve loss of consciousness. We’re seeing similar sorts of studies of AFL football players, rugby league players and rugby union players, as well as soccer players, in Australia. We were looking at the impact of those repetitive concussions. We have established evidence between boxing and dementia pugilistica, which is a form of dementia that arises from repetitive high impact concussive head injuries, but that’s specific to boxing. So the interest amongst competitive contact sports is, do we have an increased risk for seeing those sorts of outcomes in professional sports people who have repetitive injuries? There is some indication that there’s a risk. There are descriptions of a condition called CTE which involves pathological changes which have been detected in retired professional NFL players from the US. There are issues between sports, in terms of level and force of contact, that have to be worked out in terms of how they contribute. There are issues in terms of magnitude of concussion. There are issues, particularly in relation to sport, in terms of the age at which these concussions start. Most professional sports players commence their sport as children, and continue to play all the way through amateur and junior leagues. Do the concussions that happen that early on, carry more impact than the concussions that happen later on? So we don’t have the evidence yet, but there is sufficient concern at this stage that most sporting codes that involve contact sports have modified concussion rules, and we have very clear information and concussion rules particularly for junior sports. Rugby union was probably the first sport worldwide that brought in mandatory concussion reporting rules and taking players out of sport, particularly at junior levels, worldwide, and that is starting to influence every other professional code. Whether someone should be concerned about increased dementia risk from concussion, is difficult to be definitive about. There is possibly a link between the number of repeated concussions and the severity of those concussions, and dementia. That being said, the evidence isn’t firm yet, but it would most likely be dose dependent. That is, the sporting code rules would indicate that two concussions, of any form, within a season, should sideline a player for the rest of that season until medically cleared to resume playing, and that means cognitive testing to make sure that the brain functions are back to normal. So if we extend that risk, we need to monitor repeat concussions, and if a player starts to experience more than two concussions in a season, every season, they should probably reconsider their choice of sport and the potential for risks to future brain functions.
Dr Shannon Klekociuk
Stress is something we all experience throughout our lives.
What we do know about stress, is that it can put us at risk of other health complications, like issues with our digestion, increases in our blood pressure, and mental health issues such as anxiety and depression.
Stress has also been proposed as a potential risk factor for dementia.
Some studies have shown that people who report stress consistently throughout their mid-life, may be at greater risk of developing dementia later in their life.
However, the mechanism through which stress affects dementia risk hasn’t been adequately tested. Some researchers think that stress may have an indirect relationship to dementia risk. For example, it is well established that stress can increase your blood pressure. It is also established that increased blood pressure may put you at risk of cardiovascular disease. Both high blood pressure and cardiovascular disease are risk factors themselves for developing dementia.
然而，压力影响认知症风险的机制尚未得到充分测试。 一些研究人员认为压力可能与认知症风险有间接关系。 例如，已经很好地确定，压力可以增加你的血压。 还明确血压的增加可能会使您处于心血管疾病的风险中。 高血压和心血管疾病都是发展成认知症的危险因素。
So you can see that reducing your stress may help reduce your risk of cardiovascular disease, it may help reduce your blood pressure, which in turn may help reduce your risk of dementia. As another example, some studies have shown that people with stress-prone personalities, or those high in neuroticism, may be at a greater risk of developing dementia.
This may be because they spend significantly less time socialising with family and friends.
Having significantly less social interaction may contribute negatively to an individual’s overall risk of developing dementia.
Stress cannot be completely avoided, but managing our stress can be very beneficial to our overall physical and mental health.
Currently, there is no evidence to suggest a direct link between stress and dementia.
Dr Shannon Klekociuk
Lots of claims are made about various risk and protective factors for conditions such as Alzheimer’s Disease. Some of these have scientific merit and some of these don’t but, because a lot of them are discussed in the media, it makes it really hard to unpack what is a genuine protective or risk factor and what isn’t. Let’s briefly discuss some of the factors that appear to be more hype than hope.
Aluminium is a common metal found in the earth’s crust, in the food we eat and in the water we drink. It has various uses from building cars, trains and other vehicles, right through to more domestic uses, such as pots and pans, cutlery. It’s even used for some cosmetics, such as anti-perspirant deodorant. During the ‘60s and ‘70s, there was a lot of concern that exposure to aluminium might increase a person’s risk of developing dementia. Since then, there have been various studies looking at the different ways in which people are exposed to aluminium and whether this might be associated with an increased risk of developing dementia. In one of the most cited studies in this area, researchers from the UK estimated aluminium consumption via water over a 10 year period. They looked at people who developed Alzheimer’s Disease, brain cancer and other diseases that cause dementia. Their results found no support to suggest that the consumption of aluminium via water would increase your risk of developing Alzheimer’s Disease, brain cancer or any other disease.
Even exposed to aluminium at high levels, for example a chemical spill, has not been shown to have long term consequences for brain health. To date, there is no evidence that supports a link between every day aluminium exposure and an increased risk of developing diseases like Alzheimer’s or other diseases that cause dementia.
Professor Kaarin Anstey
When I studied undergraduate psychology, we were told that you were born with a set number of brain cells. And then all the binge drinking at uni, and all the things that you did, meant you lost more and more brain cells, and that the brain couldn’t renew itself, and there was no capacity for change. What’s happened, there’s been a revolution in neuroscience, in our understanding, and we now believe that the brain is plastic, and it does continue to change, and it can benefit from these lifestyle changes, and through things like being mentally active, and cognitively engaged, and through further study. So, you can fix your health risk factors, and you can also build what we call cognitive reserve, through cognitive stimulation. And this is what we think is the real positive story around the prevention of cognitive decline and dementia.
当我学习本科心理学时，我们被告知，你带着一定数量的脑细胞出生。 然后，你做的例如上大学时疯狂饮酒所有的事情，意味着你失去了越来越多的脑细胞，我们过去认为大脑不能自我更新，没有能力改变。 现在发生了什么？神经科学发生了革命，我们现在相信大脑是有可塑性的，它确实继续在改变，它可以通过这些生活方式的变化，通过心理活跃和认知参与，并通过进一步研究之类的事情受益。 所以你可以修复你的健康风险因素，你也可以通过认知刺激来建立我们所说的认知储备。 并且这是我们认为是围绕预防认知衰退和认知症的真实有积极意义的故事。
I think if you go back to what we know about neuropathology that underpins the dementias, the two most common causes are the Alzheimer's pathology and vascular pathologies. Both of those accumulate slowly, through middle age, with things like high blood pressure and lifestyle risk factors. The idea is that through risk factor modification, we’re slowing down the laying down of that neuropathology. That’s why we think that these modifications, the earlier you start them, the greater the benefit will be. There is going to be some inevitable brain ageing, and then there are going to be some risk factors that you can’t help happening to you, like a head injury, for example. It’s our understanding of this development, over a long period of time, that leads us to think that we can delay the onset of cognitive decline and dementia. In fact, we’re seeing that in some of the epidemiological studies now, where we’ve compared cohorts of the same age but born in different years, and we’re actually seeing that their trajectories of cognitive decline are different, and the more recent cohorts are spending more of their life in what we call cognitive health, before they start to decline and develop dementia.
With population ageing globally, we’re going to have enormous numbers of people with dementia; we already do have a huge number of people with dementia now, and it’s just going to increase over the next 30 or 40 years, and we don’t have a cure. Really, the only approach that we have at the moment is risk reduction. Hopefully, in the meantime, people will develop treatments and cures for Alzheimer's disease and dementia, but until then, risk reduction is the best method that we have to address the projected prevalence and incidence of dementia with population ageing.
随着全球人口老龄化，我们将有数量惊人的认知症患者; 现在我们已经有大量的认知症患者，它只会在未来30或40年不断增加，并且我们没有治愈方法。的确，我们目前唯一的方法是减少风险。 希望在此期间，人们将开发针对阿尔茨海默氏病和认知症的治疗方法和药物，但在此之前，降低风险是我们必须解决认知症与人口老龄化的预计流行率和发病率的最佳方法。
Dr Ben Shüz
One of the most striking barriers to changing behaviour, to reduce dementia risk, is the fact that there is such a huge distance in time between what we’re doing now and when we might get the outcome. This is a problem that is very common to a lot of health behaviours. If I’m increasing my physical activity now, there might be a few short-term benefits - I’ll lose some weight, I’ll gain muscle tone. But the big beneficial outcomes, they’re very far in the future - so I may not get heart disease, or I may not get type two diabetes. If you’re already at high risk for those things, you still have a pretty large delay in when the, what we call reward, will come about. And that’s very different from health risk behaviours. You get immediate reward from eating a Danish. Smokers get an immediate reward when they smoke a cigarette. If you have a glass of wine, it immediately tastes good, and the cost will come later. So one of the major barriers in reducing dementia risk is really the difference in onset of costs - it’s no fun starting to be more physically active, it’s no fun changing your diet, and the rewards, which may or may not come after 20, 30, 40 years in the future, not getting dementia. And we’re pretty bad at dealing with, what we call, delayed gratification. That is, if we’re not immediately gratified or rewarded for what we’re doing, we have problems in keeping up behaviour changes. So I’d see that probably as one of the major cognitive barriers to changing behaviour in order to prevent dementia.
改变行为从而减少认知症风险的最明显的障碍之一是，事实上，在我们现在做的事情和我们可能得到结果之间有一个巨大的时间距离。这是一个很常见的很多健康行为的问题。如果我现在增加我的体力活动，可能有一些短期的好处 - 我会减肥，我会获得肌肉紧张。但是大的有益的结果是在很遥远的未来- 我可能不会得到心脏病，或者我可能不会得到2型糖尿病。如果你已经面临这些事情的高风险，你仍然有一个相当大的延迟将会发生，我们称之为奖励。这与健康风险行为非常不同。你会通过吃丹麦酥皮立即得到奖励。吸烟者在吸烟时会立即得到奖励。如果你喝一杯葡萄酒，你可会享受美酒的好味道，而付出的代价来得晚。因此，减少认知症风险的主要障碍之一是，减少认知症风险真正开始付出代价事件上的差异 - 没有乐趣开始更多的身体活动，改变你的饮食是没有乐趣和奖励，可能或可能不会在未来20、30、40年得认知症。当我们在处理我们称之为延迟的满足，感觉是非常糟糕的。也就是说，如果我们不能立即从我们正在做的事情感到满意或得到回报的话，我们坚持进行这种行为的改变就会有问题。所以我认为这可能是改变行为以预防认知症的主要认知障碍之一。
There are some challenges with regards to health behaviour change, when we look at different age groups. The behaviours that are recommended might differ. Different behaviours are more or less important at different stages in our lives but, most importantly, what we think we can or should do changes a lot during our lifetime. For example, we know that, in many older adults, experiences such as increasing difficulties walking up the stairs, increasing difficulties remembering things, increasing difficulties concentrating, are attributed to old age per se, so people think, “Ah, I can’t climb up the stairs. That’s probably because I’m getting old,” or “I keep forgetting things. That’s probably because I’m getting old,” but it may actually be early signs of an illness. So, by thinking that changes in our health are a natural part of ageing, we tend to be less motivated to do anything about it, because, after all, you can’t change your ageing process, can you? But if we think about those things as risk factors, and as things that can indicate that something could go wrong, we might be more inclined to do something about this. So this is a very, very important risk factor or barrier to behaviour change that we find in older age. In younger age groups, barriers to successful behaviour change have to do with what I’ve been talking about before, and that is the delay in gratification that we get from engaging in a health behaviour. So we may not get a heart attack in 20 years, we may not get type one diabetes in 20 years, but that’s not particularly relevant when I’m in my 40s, and it’s even less relevant when I’m in my 20s, because that is all so far away. So these might be some of the more specific barriers that are related to different age groups.
当我们观察不同的年龄组时，在健康行为变化方面遇到一些挑战。被推荐的行为可能不同。不同的行为或多或少在我们生活的不同阶段是重要的，但最重要的是，我们认为我们可以或应该做的改变，在我们的一生中很多。例如，我们知道， 许多老年人当走上楼梯时困难增加，记忆的事情变得更加困难，更加难以集中奖励时，往往将这些事情归因于年纪大了，所以人们认为，“啊，我不能爬上楼梯了。这可能是因为我变老了，” 或 “我老忘事 。这可能是因为我变老了”， 但这些可能实际上是疾病的早期迹象。所以，如果认为我们的健康的变化是老龄化的一个自然部分，我们往往会没有动力去做任何事情，因为毕竟是你无法改变你的衰老过程的，你能吗？但是，如果我们将这些事情看作是风险因素，并且是可能出错的事情，我们就会更倾向于做这方面的事情。所以这是一个非常非常重要的风险因素或我们发现在年龄较大时改变行为的障碍。在年轻的年龄组，其成功进行行为改变的障碍与我在前面一直在谈论的有关，那就是我们从健康行为得到满足的延迟。所以我们在20年内可能不会有心脏病发作，我们可能在20年内不会得1型糖尿病，但是当我40岁时，这不是特别相关，而且当我20多岁时，相关性更低，因为所有都离得还这么远。因此，这些也许是与不同年龄组相关的一些更特殊的障碍。
Well, there’s good news. It’s really never too late to change your health behaviours. There are a couple of really fantastic studies that I like to use as examples in my lectures. There’s a great study from Sweden, in which researchers followed up a group of elderly - and with elderly, apologies, the researchers meant women aged 65 and over - and they were able to follow them up for a period of a year, and then they were able to get mortality data off those participants later on. That is, they were able to track changes in their physical activity over a year and then see whether people who changed their physical activity were more or less likely to die earlier over a long period of time. And the interesting thing they found is that people who were not active at the beginning of the year, but became active over the course of that year, had the same reduced mortality risk as those older women who had been active in the first place. And the same holds true for ceasing to be active. Those women who ceased being active over the course of the year had a very similar increase in risk of mortality over the course of that time span than the women who had not been active in the first place. So that shows us it’s really never too late to change health behaviour.
好消息是改变你的健康行为真的永远不会太晚。有几个真正了不起的研究，我喜欢在我的演讲中做例子。有一项来自瑞典的伟大研究，研究人员随访一群老年人 - 抱歉，研究人员的意思是指65岁及以上的女性 - 他们随访了她们一年，然后他们获得了这些参与者的死亡率数据。也就是说，他们随访了他们一年多的身体活动的变化，然后观察改变他们的身体活动的人是否或多或少可能在较长时间内早死。他们发现的有趣的事情是，那些在年初不活跃，但在那一年后来变得活跃的人，与那些一直活跃起来的老年妇女的死亡率降低程度相同。这同样适用于停止活动的情况。那些在一年中停止活动的妇女在这段时间内死亡的风险与没有活跃的妇女相比有非常相似的增加。这向我们表明改变健康行为从来没有太晚。
There are also really great studies in very old, older adults, aged 85 and over, both in stationary care and living at home, in which researchers found that increases in physical activity had a very, very beneficial effect on everyday functioning and activities of daily life. So no, it’s never too late to do anything about that and change behaviour.
It’s really tricky to know whether and when we’re reducing our dementia risk, because there is no established biomarker, and there is no one thing that will tell us that we’re actually doing something good for our health, and that we’re doing something good to reduce our risk of dementia, but we know a lot about the risk factors for dementia, so we know that, if we’re doing something about those, we’ll be reducing our dementia risk. So, if we are following behavioural recommendations to reduce the risk for cardiovascular mortality, if we’re engaging in the behaviours that are recommended to reduce the risk for type two diabetes, and those kinds of things, we know that we are reducing the risk factors for dementia, even though there is no really good way of telling whether it actually does reduce the risk.
知道我们是否以及何时在降低认知症风险是真的很棘手，因为没有已确立的生物标志物，没有一个事情会告诉我们，我们实际上在做一些对我们的健康有好处的事情，对减少认知症风险有好处的事情，但是我们知道很多关于认知症风险因素，所以我们知道，如果我们做和那些有关的事情，我们将减少我们患认知症的风险。 因此，如果我们遵循行为建议来降低心血管死亡风险，如果我们参与推荐降低二型糖尿病风险的行为，以及那类事情，那么我们知道我们正在降低风险 认知症的因素，即使没有真正好的方法来告诉它是否真的降低了风险。
So some people might think that dementia is a natural part of ageing, which it is not, and therefore might think that doing anything against dementia is really futile. This kind of belief is one of the major barriers to changing health behaviours in old age, because many people think that health related changes in older age are a natural part of ageing, when they’re not. So many people could think that, “oh, my memory’s fading a bit, I have difficulties in remembering a phone number” - that these are natural things that occur with ageing. They may be, but they may also be indicators of dementia, so it’s always worthwhile having those checked out. And we know that from different health behaviours as well. People may think, “I’m having difficulties climbing up that flight of stairs, I’m finding it increasingly difficult to bend down, but that’s a natural part of ageing, I can’t do anything about that.” And they’re actually morbidly obese. So thinking that something is a natural part of ageing can prevent us from actually doing something against it, and recognising that your memory changes, recognising health changes in general, are always something that you should take seriously and never think that they are a natural part of ageing.
因此，有些人或许认为认知症是老龄化的一个自然部分，因此可能认为对认知症做任何事情都是徒劳的。这种信念是改变老年人健康行为的主要障碍之一，因为许多人认为老年人健康相关的变化是老龄化的自然部分，其实不是这样的。因此很多人可能会认为，“哦，我的记忆已经减退了一点，我在记电话号码时遇到了困难” - 这些都是随着年龄增长而发生的自然事情，他们可能是因为这个原因，但这些也可能是认知症的指标，所以总是值得将那些检查出来的。我们也知道那些也来自于不同的健康行为。人们或许会认为，“我爬楼梯很困难，我发现越来越难弯下腰，但这是老化的一个自然的部分，我不能做任何事情来改变这些。”他们实际上是病态肥胖。因此，认为某事是老化的一个自然部分会阻止我们切实做些事情来对抗它，并且认识到你的记忆变化和一般的健康变化总是你应该认真对待的事情，永远不要认为它们是老化的一个自然部分。
So if I were to give you a take home message, it’s this: don’t think that as you’re getting older everything is getting worse. So, many health-related problems that we’re experiencing as we’re getting older are actually health problems. They’re not part of natural ageing. If you’re worried about these kinds of things, see your GP or talk to someone. Not all the changes that we experience as we’re getting older are normal. Some of them might indicate illnesses. But, at the same time, there is good news, which is that it is never too late to change health-related behaviour. We know from research that, even in old age, increasing physical activity, changes in diet, can be really beneficial for your health. And, even though there is no dedicated biomarker or good indicator of your dementia risk, we know what the risk factors are. So, if you’re doing something about those, if you’re keeping healthy, you’re actually doing something good for your brain health and for your risk of dementia as well.