Josh: [00:00:00] Welcome to Better Brain Fitness, hosted by doctors Josh Turknett and Tommy Wood. In this podcast, we will explore the frontiers of how to keep our brain fit and healthy so that we can perform at our best and do the things we love for as long as possible. Let’s go.
Welcome to another episode of Better Brain Fitness. Once again, I’m joined by my co-host, Dr. Tommy Wood. Hello. Hello. All right, so we have another question, submitted by one of our listeners. Once again, if you have a question for us or if one pops into your mind as you’re listening to this episode, please feel free to send our way.
There’s a link in the show description to where you can do that. Or you can go directly to brainjo.academy/question and you’ll see where you could submit it there. Okay, so Tommy’s gonna take the first stab at answering this question today, and he’ll read it out to us. [00:01:00] So go for it, Tommy.
So we have a question from Peter, although actually we’ve had several versions of this question, so hopefully we can tick them all off at the same time. But Peter asks, if someone has grandparents or parents who suffered from dementia, how much does that increase the likelihood that they will be afflicted?
So obviously there are gonna be a number of people who are concerned because you know, a close family member has, has had some form of dementia and maybe they’ve had to care for them or they’ve seen how it’s affected their lives or it’s affected their family, and they want to determine how, how likely it is that they will then have some either related condition or age-related dementia or age-related cognitive decline that affects function significantly.
So it’s a great question, and we talked briefly in our first episode when we sort of outlined some of our thoughts about this whole process about the, the genetic component of late onset Alzheimer’s disease or age [00:02:00] related dementia and that’s probably where a lot of the, the question comes from, but actually not necessarily all of the answer comes from there. But it’s a good place to start. So, based on various evidence, we think that genetics make up somewhere between four and 10% of your risk of Alzheimer’s disease. And obviously half of your genes come from one parent and half from the other parent.
So there will be some underlying genetic component and some of that will be inherited from the family member that, that you are thinking about. However, it’s obviously a very small. Part of overall risk. And we’ve talked about previously about the fact that even quite significant risk genes like the, APOE four genotype only really express themselves in terms of increased risk of dementia in certain environments, which for most people is the average modernized westernized environment, which is probably the environment that you [00:03:00] live in if you are listening to this podcast and sending us questions. So that is an important consideration. However, we can modify that risk, we believe almost entirely by manipulating that environment or putting ourselves in an environment where that’s not necessarily having the same effects based on diet and sleep and exercise and those kinds of things.
So genetics play a role, however, they’re probably largely modified by the environment and most of that is something that you hopefully have some control over. So where I think risk of dementia does cluster in families is not just due to shared genetics, but it’s due to shared environments.
So if you, you know, you grew up in an environment, you obviously ate the same food, you lived in the same house you often have the same physical activity, you may have the same types and of education and jobs, you know, there could be a huge amount that’s very similar. That’s conveying [00:04:00] risk across families.
We know that if you have a parent who has say touch of diabetes or obesity, then you are more likely to have that as well. And that’s largely due to shared environments as well as a small aspect of genetics and dementia seems to be the same. So then you can say, well, what is it about a shared environment that I maybe have some control over, that I’m willing to change?
So you could think about this family member that you are, you are concerned about the fact that they had dementia, you’re concerned about your own risk, and you can think about some of the things that, that we’ve mentioned in terms of risk factors for dementia. So physical activity body composition, metabolic health, you know, say pre-diabetes or, or diabetes, sleep diet quality, sort of getting at adequate nutrients in the diet and. And often when I, I speak to people about this and they ask this question they say, oh, yeah, do you know what? I recognized these things in in my parent, and these are all things that [00:05:00] I’ve changed. Or these are things that I don’t do and, you know, other things that I haven’t mentioned. Smoking, significant alcohol intake, and they’ve made a conscious decision to have a different environment and a different lifestyle from this family member who had dementia. And so then I think the large majority of your risk is probably being mitigated if you’ve changed your environment and you’ve changed your lifestyle. So to kind of summarize, and we can, you know, over time we’ll sort of really dig into each of these things, bit by bit as, as we need.
Obviously dementia does sort of cluster in families, but a large part of it is probably due to shared environment rather than shared genetics. And the sort of conservative estimate, and, and I think it’s, it’s probably more than this conservative estimate, is that at least 40% of dementia is. Is modifiable and preventable based on lifestyle in the environment.
My guess is it will at least be the majority of cases. So more than that. And that is something that, that hopefully you have some control over. So, the best place to start is to identify [00:06:00] common risk factors that you have with a family member who had dementia, maybe that’s the place to start because it can be a bit overwhelming.
Like I’ll list 10 different things or 15 different things that are important for dementia risk and you might say, well, where should I even start with all of this? And then, you know, maybe some of the genetics come into play with respect to which things you are particularly susceptible to.
So that’s a, a nice place to start, at least. Low hanging fruit maybe to identify you know, a risk factor that was obvious in the lifestyle and environment of a family member and, and say, well, I, I’ll make sure that that’s something that, that I start with and see if I can make some, some improvements there.
So that would, that’s generally how I’d approach that question. And I think the good news is that even if you have a family member with dementia, the large majority of the risk in yourself I believe is modifiable with, you know, all the things that we’ve been talking about.
Josh: yeah, those are great points.
And I think it’s kind of a double-edged sword. On the one hand, it’s great news, family history really isn’t, you know, does not [00:07:00] determine your fate. On the other hand, most cases are occur in the absence of any family history, right? Mm-hmm. So, yeah, so it’s really that ultimately regardless, it’s our environment that matters. Right? And, even that risk, you know, the four to 10% risk, the amount that that genetics contribute that is, is in the environment of today. Right, exactly. So there’s, there’s hard of our individual environment, but there’s also our collective environment which we share.
So if you were to, to look, do that same analysis pro in like hunter gatherer populations, you probably find a much, much smaller number. Right. Because you’ve got, you know, such low risk there, but I think that as you say, this is a super common question and I think that most people tend to think that genes play more of a role than they do. Many people who have that, they have a family member think that that means it’s likely they’re fate. And I think there’s, that’s still kind of a lingering impact of the genetic era, you know, when we were this, this rush to sequence the genome, you know, for good reason, [00:08:00] but we thought that was going to unlock a lot more than it did in terms of our therapeutics and what we could do about disease, because we thought that the genes played such a big role, and I think still that’s a, a popular conception, but the reason it didn’t lead to more is because they actually play much less of a role than we thought, and they’re so contingent on environment.
So we, you know, kind of had this idea that genes were a recipe book and the recipes were just read out and there wasn’t kind of a whole lot you could do about that, right? But now we know that lifestyle affects us all the way to what genes are transcribed, what genes are expressed when.
And so that process of how and when they’re transcribed probably matters more than the actual genes themselves, and undoubtedly one of the reasons why lifestyle so profoundly shapes our health is because it’s capable of influencing things all the way down to, you know, gene transcription.
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Okay, thanks again, Peter, for your question. Again, it’s a common one. I’m sure it’s a topic we’ll probably come back to at some point and I think there’s some, there’s some other nuances regarding genetic impact and other conditions that are related to, you know, cognitive decline. And again, if you have questions yourself, we’d love to hear from you.
There is in an option to send [00:10:00] us your questions either via text or audio. And we’d love if you’d submit an audio question because we’d love to hear, hear your voice. So again, there’s a link in the show description to where you can submit your questions and you can also go directly to brainjo.academy/question.
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