Comment by inglor_cz
16 hours ago
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 Test is repeated every day you get in the cab.
If you get into a black cab in London and ask to be taken to any location, anywhere within 6 miles of Charing Cross, that driver will know immediately the right route to take without satnav. To get to that point they need to know 25,000 streets and many, many landmarks - statues, museums, galleries, restaurants, hotels, and so on.
I used to regularly drink with a cabbie in London, and he said that every time somebody got in the back his heart rate would rise, as he'd realise he's "on" and about to have to work out where to head from scratch. Within 30 seconds he'd have every step of the way worked out, down to which lanes at which intersections, no matter where in London he was or where he was going.
That's the thing that's likely going to reduce Alzheimer's.
The point of the test is that you know how to traverse london, and you also know and have a feel for patterns in traffic.
In the same way that you have code smell.
Granted, some use GPS, but most only really use it for pickup