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Modifiable risk factors

Professor Craig Ritchie talks about the concept of risk and the modifiable risk factors related to brain health.
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In this video, we’re going to take a look at what risk is and how this can be applied to brain health. We’ll also dive deeper into the known modifiable risk factors for poor brain health or dementia. Simply put, you can think of risk as a chance or likelihood something will affect your health and the potential consequences which follow being exposed to that risk. Likelihood times consequence equals risk. Assessing risk for a disease is often a complicated balance of weighing up an individual’s genetic and other health related exposures that accumulate throughout life. But risk doesn’t automatically mean something bad will happen. Different characteristics called risk factors influence whether they’re a health risk is lower or higher.
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These risk factors are also commonly interlinked. Meaning it’s trickier to tease out individual factors with any high degree of certainty. There is work underway to undertake tailored individual profiling of the risks and brain health, and to be able to detect the early signs of disease in the brain as well. These assessments will inform how an individual can reduce their risk of brain diseases developing or progressing. We know that there are a number of lifestyle areas we can each take action on in the meantime, they will help to maintain or even improve brain health. And we’ll discuss these shortly. But broadly speaking, when we consider a risk, we can place things in two categories.
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Number one, fixed or non-modifiable risk factors, and secondly, modifiable risk factors. Fixed are the things we can’t really do anything about it, whereas modifiable risks have the potential to be addressed or even eliminated. Let’s take Alzheimer’s disease, an example. When we think of the fixed risk for developing Alzheimer’s disease, two main areas of focus are age, and genetics, or family history. The link between age and Alzheimer’s is a prominent straightforward one. Our risk increases as we get older. However, less straightforward of the connections between our genes and our Alzheimer’s risk. We all inherit two versions of each of our genes, one from each parent.
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And in general, people of a parent affected by Alzheimer’s disease statistically have a higher risk themselves. Having two affected parents will increase the overall risk even further. With the degree of this with each individual is hard to predict with certainty. We’ve talked here about risks and discussed an example. But there are many more risk factors to consider when building an overall profile of brain health risk. The majority of them we can modify through lifestyle decisions across the life course, physical activity and exercise being a critical one. Let’s turn our attention now to the modifiable risk factors for brain health. If you’re interested in learning more about genetics and Alzheimer’s, consider checking out
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week 2 of the Understanding Brain Health: Preventing Dementia MOOC, which is also hosted on the future of our platform. When it comes to brain health, the modifiable risk factors for which we currently have the greatest level of evidence have been compiled in what’s called the Lancet Commission Report in dementia prevention, intervention, and care. This report looks at the sum of all existing evidence around risk factors and concludes that eliminating 12 potentially modifiable factors would lead to a projected 40% decrease in the total cases of dementia. In other words, if we were able to wave a magic wand and completely remove the 12 risk factors from the planet, we would see 40% less people developing dementia. This is huge.
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Therefore, this proportion of overall dementia cases is in theory preventable. In practise though we don’t have a magic wand. And you’ll notice from studying the list of modifiable factors that many have complex and overlapping causes. However, what this summary of the evidence base does give us some really clear key areas to focus attention on for effective prevention. What’s good for the brain is good for the heart. Our brain is an energy intensive organ, and as such it’s also a very thirsty one. If you imagine it’s like a high powered sports car, rapidly consuming fuel. Our brain acquires a rich blood supply to perform at its best.
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And although the brain only accounts for about 2% of our total body weight, it receives almost 20% of blood output from the heart. So actually in many ways, the brain is a very simple organ. If it’s got a good blood supply then our blood supply is full of oxygen and good nutrients and we don’t do anything by injuring it, then you’ll have a healthy brain. Looking at the list of 12 known risk factors, we can clearly see a link between what we classically think of as heart health and brain health. So for instance, hypertension, excess alcohol, obesity, smoking, physical inactivity, air pollution, and diabetes, are all known to affect our cardiovascular health.
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We now know it can also affect brain health too. But more specifically cognitive stimulation both socially and intellectually is important throughout our lives, and particularly, we believe for brain health. We also see that those so not so directly related to cardiovascular health. The cluster that I’ve mentioned before, are relevant for brain health like education and social interaction. This reinforces a belief that challenging our brains on learning new skills throughout life, maintaining social links is going to be great for brain health. This stimulation is important for maintaining effective functions of our brain but also to build up resilience to disease processes.
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For instance, we know from post-mortem research studies that not everyone is affected equally by neurodegenerative diseases being present in the brain. So for instance, two individuals might be classed as having a very similar risk or degree of pathology in the brain, a post-mortem can of actually had very different presentations in life in terms of the severity of symptoms and impairments they experience in life. And one leading theory for why this might be is explained through the concept of cognitive reserve.
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So the idea behind cognitive reserve is that if we have a richer network of pathways built up in our brains through a greater number of interlinked brain cells connecting with each other, then we may be able to tolerate a certain degree of damage without experiencing as many symptoms. So in other words, there’s a richer network of brain connections makes us more resilient and able to adapt and cope with earlier brain disease processes. So, one way to think about this is to picture another car travelling along a road to reach its desired destination. Let’s imagine the route becomes blocked, say, by a tree falling on the road.
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If there’s only one possible route to take then the car is stuck and can no longer reach its destination - Figure A. However, if there are a multitude of alternative routes to choose from, then we can perhaps make a diversion, take another route, and still arrive in that desired destination - Figure B. This is a basic principle of cognitive reserve. The greater the network of possible pathways or brain connections we’ve built up over life, the greater our capacity to adapt and reroute when disease process, much like a fallen tree, disrupts one of those paths. The 12 factors are not the only risks that we know of. The Lancet report only includes areas that we have the best quality evidence for.
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More research is adding to our knowledge all the time. And undoubtedly, this list of modifiable factors will continue to grow or change. For instance, sleep isn’t on the list at the moment but we think that’s really important. Research findings will also continue to chip away at the risk unknown proportion. What factors can you think of not covered here that might be linked to risk for or protection from the neurodegenerative diseases that cause dementia and poor brain health? Have a think about it, and maybe put some of your ideas, your thoughts, your comments in the comment box after the video. Thank you very much.

There are a number of risk factors we can influence to build our brain health capacity, many of which are similar to how we support and protect heart health.

In this video, Professor Craig Ritchie talks about risk, 12 modifiable risk factors we know about, individual risk profiling, and more!

What factors can you think of, not covered in the video, that might be linked to risk of poor brain health? Feel free to put some of your ideas in the comment area below.

Remember to also check out and save the accompanying infographic (see ‘downloads’ below).

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