Getting lost in familiar places
Developmental Topographical Disorientation, or DTD, is the inability to orient yourself in familiar locations; people with it cannot remember their way around buildings that they live and work in every day. And whilst these symptoms are not uncommon in those with brain damage or neurodegenerative diseases like Alzheimer’s, DTD appears to affect those with no form of cognitive defect. Hugo Spiers spoke to Will Tingle about what we know already about DTD, and how he hopes to find out more.
Hugo - There are many bits of your brain involved in navigation, and that's partly because navigation is one of those skills that varies what you're doing. So if I'm going to the shops <laugh> at my house, I'll be navigating, I don't want to make the wrong choices of streets to get to the shops. It's a very different bit of my brain. It's a bit of the brain, like they're called the striatum that I'll be using for that. But there are other bits of the brain if I've gone somewhere new and I'm trying to figure my way back or my road to the shops is closed and I need to figure out. where we think we might use a mental map inside our head. And then are other bits of the brain in particular, a bit called the hippocampus, which are known to be important for that type of navigation. So which bits of the brain do we use for navigation? Depends very much on what type of navigating you're doing.
Will - I'd like to think that I'm somewhat good at navigating, but I know there are people out there that aren't. What's the difference, do you think, in people's brains that causes this disparity?
Hugo - There would be a number of factors that will relate to that. The very likely strongest one is just how your brain got built and developed when you were small. We all inherit things from our parents and some of that can be an aptitude for navigating well. But as you grow up, there'll be different things that expose you to different challenges that can help make you a better navigator. Things like learning to drive lots of time spent out traveling around different professions you might pick up. All sorts of things that could harness those bits of your brain for navigation. So there's a whole lot of different experiences.
Will - But whilst there's a fair amount of people that perhaps struggle slightly with navigation, there's a huge difference between them and the group of people that you are starting to look into. And that's people with developmental topographical disorientation or DTD. What does that mean?
Hugo - We all talk about how some people are good at navigating some not so good. But there's clearly a very distinct group of people who really struggle to find their way. And the key defining feature of that is really kind of being lost in buildings they've worked in for years. They just become more easily disoriented. Go into the toilet, come out. Which way is it? It's hard to know and all of us can struggle with other times, but these people would really explain this as a problem for them. It's not a medical condition, it's just something you're born with. You're not good at this particular skill. And it affects people's lives. And we'd like to understand our experiences more because then we can try and understand what is difficult for them. And the value in that is helping improve these kinds of tests that are useful for clinicians, but also to help people who make buildings, hospitals, transport hubs, cheap stations to account for these people who are struggling. What is it we can do? Where does it go wrong? What is it that could help them to navigate better? So that's our new research and as scientists, the best people who come in are the ones who struggle <laugh>. If someone turns up and does their test perfectly, it's not very useful for us. People that make mistakes are extremely helpful. Even a few to many. They really teach us things that we need to know about the brain.
Will - We actually recently heard from Alix Popham, the former rugby player who was diagnosed with early onset dementia. And he said that he lost his way home on a really familiar route and that was a sign that he had this dementia. But you can say with confidence that there's no sign of brain injury or neurodegenerative disease in people with DTD.
Hugo - That's absolutely right. So there's a big difference that these people who have developmental topographical disorientation, they may well not realise they've got it just all their lives been a little bit more challenged at navigating. And, if they were to go and read up on developmental topographical disorientation, they may realise, oh, that describes me. But you're right, it's not a condition that's linked to dementia at all. So it's a separate process. It appears to be something you're kind of born with and develop this inability to orient in space. But for those people who have early onset Alzheimer's dementia, it's really like a profound loss of 'where am I?' So the distinction here is that someone with DTD wouldn't feel confused in the same way or it's not like a change in their experience, but more something they've always had to adapt to. So really extremely helpful to understand what it's like for people with DTD, but to also relate that and distinguish it from people who have the early onset Alzheimer's dementia. So if anyone is able to help us with this research, we really are looking to try and help address experiences for a range of people who have issues with navigation, not just those with dementia, not just those with, DTD, but across the board.
Will - Because presumably if you can help one form of memory loss, you might be able to help them all.
Hugo - Absolutely. We can try and distinguish. So, my assumption is that someone with DTD would likely make good decisions and make very clear choices and understand what they're doing, but they just find orientation hard. And so I think we will see some really interesting choices they make that distinguish their problems from people who are really struggling with the early stages of dementia.
Will - So aside from being unfamiliar with familiar locations, is there anything else people who think they might have this could look out for?
Hugo - The other symptoms for DTD are really being suddenly kind of confused if you've turned around, gone between rooms and you're not sure which direction you're facing. So being suddenly disoriented in space can be one of the key symptoms. And yeah, struggling to find your way in familiar spaces. So lots of people will have a hard time navigating new places. If I go to a new city, I'll struggle, but someone with a DTD would struggle in a place they've been for some time. They just have a hard time making a mental model in their head of the environment.
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