Comment by walthamstow
19 hours ago
> In one landmark 2000 study, neuroscientists compared the brains of licensed London taxi drivers with those of people who did not drive cabs.
Location is very important here. London cabbies have to pass The Knowledge which is an extremely difficult memory exam that only people with particular kind of brain can do.
They have to memorize 25,000 streets. The test is no joke. [0]
[0] https://www.youtube.com/watch?v=ur61kzXjvN8
Would they typically also relearn this at intervals. If you take 5000 rides a year, maybe 2000 streets that is 23000 you didn't get to remember though experience.
They also have to remember where roadwork is/was and what kind of traffic is best/worst at a given time.
There's a fantastic Tom Scott video on it https://www.youtube.com/watch?v=ZmWREtcDVBE
Test may be no joke. But the test is also a joke in the world of GPS and Uber.
I am glad Uber plowed through various stupid regulations constraining supply to bring a service with drastically more supply.
People who would pass The Knowledge test might already develop dementia at a much lower rate.
They could also develop it at the exact same rate and mask it effectively. Had a very sharp family member who was completely lucid through all of dementia, it was like watching a tape rewind. Got to meet each decade's version of them over a couple of years. Towards the end they were completely normal
I don't understand. Do you mean they were lucid, but they believed they were living in a different year? Like thinking adults were still children in school and wondering when dead people were going to call? That kind of thing?
So towards the end it was like it went away?!
Plausible, but then you'd expect to find the same effect in other people who passed similarly demanding tests once. For example in people who studied something geometry-heavy.
Also, The Knowledge Test is, IIRC, passed only once and then you do not have to retake it for the rest of your career.
If a test passed in your 20s or 30s predicted accurately a much lower incidence of Alzheimer's in your 60s, that would be a remarkably strong early signal. Not impossible, but worth extra scrutiny. For the vast majority of old age conditions, we cannot predict them so long in advance.
The first study referenced is in the US, and across 443 occupations.
Correlation and causation and all that.
A number of the women in my wife's family have been diagnosed with Alzheimers. All of the women I know in her family also hate driving, because they find it very stressful.
It's plausible that people prone to Alzheimers are less likely to be comfortable driving.
Best wishes for your wife's and your continued health.
> that only people with particular kind of brain can do.
That's yours speculation, isn't it?Because if so, it would corroborate the same conclusion, i.e. if you exercise your memory regularly, you are less likely to develop Alzheimer's.
Indeed. Elsewhere in the world taxi drivers just follow the GPS.
We had taxis long before GPS.
When I was in my early 20s I had a job delivering pizza. I very quickly learned the delivery area, I knew pretty much every street and alleyway and shortcut to get from one place to another. Much smaller than London but I think the human brain is very good at remembering routes and where things are in an area, as this would have been an evolutionary advantage (go out hunting and be able to find your way back). No GPS, didn't even carry a map with me. We had a large map on the wall at the store, and if I had to deliver to a street I didn't recognize I'd find it on the map, see where it was relative to the streets I did know, and then I never had any problem finding places.
There weren't a lot of taxis outside of major cities. I think widespread GPS allows ridesharing apps like Uber and Lyft to exist in suburbs and other places where taxis weren't a thing before, because it dramatically lowers the bar.
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My 2019 car had the cardinal directions in the mirror (N, NE, E, ES, S etc). My 2025 does not anymore. I hate it. I think it helps to get that baseline of orientation, and then you look at the street numbers, and it all starts to come together.
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Same. First thing they had me buy was a map book with all the local neighborhoods. The map on the wall helped get shortcuts from others. This is where I learned the difference between the different kinds of shortcuts. Some saved time, others distance, and some even potholes. It was a fun time.
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I suspect GPS has made this much worse. I shining example was an Uber I got in Chicago, where GPS doesn't work well due to all the buildings. The guy drove around the same block 3 times, blindly following the GPS. It was infuriating.
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Maybe when they're new. In time they tend to learn the shortcuts that the apps don't show and ignore navigation here and there.
There is (or at least - was) a similar test for Paris taxi drivers. They needed among others to explain turn by turn the drive between two places indicated by the examiner.
Today this knowledge is arguably less useful.