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And how would you control for the causal possibility that those who will eventually develop Alzheimer's early on might tend to have undetectable memory issues that prevent them from becoming taxi drivers in the first place? You can't control for profession, since that's behind the very claim itself.

The study accounts for that.

Delay your aging by using your brain a fuck ton, all the time, learning brand new things nowhere near anything you already know.

Studies typically use regression to account for stuff like that. CBA to look at the article, but I bet any money that's controlled for.

They are likely studying individuals that retired without getting fatally stabbed or shot on the job.

As the paper points out that's accounted for in the analysis, because shockingly enough to most internet commentators researchers know that they need to control for confounding variables

https://www.bmj.com/content/387/bmj-2024-082194

" (...) After adjusting for _age_, sex, race, ethnicity and education, roughly 1 in 100 taxi and ambulance drivers died of Alzheimer’s, compared with 1 in 60 people overall."

That's very interesting but why do taxi drivers have a job that lowers life expectancy? Is it because they're sitting too much? Or because they're inhaling CO from cars too much? Or staying inside (the car) too much? Or is it just stressful?

For from the look of it it doesn't look like an exceptionally hard job (btw a brother of mine did years of "VTC": "Vehicule de Tourisme avec Chauffeur", basically high-end taxis without the "taxi" logo).

Ah, the typical cheap HN reaction to a paper, along with "correlation is not causation", and as usual, for things already factored in into it.

De Niro is 82, no Alzheimer's. /s

They have to memorize 25,000 streets. The test is no joke. [0]

[0] https://www.youtube.com/watch?v=ur61kzXjvN8

The first study referenced is in the US, and across 443 occupations.

> 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.

People who would pass The Knowledge test might already develop dementia at a much lower rate.

Indeed. Elsewhere in the world taxi drivers just follow the GPS.

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.

True, though the article does also mention another study not based on taxi drivers, but just living in high spatial complexity ZIP codes puts you at a lower risk.

> Research on cognitive maps points toward the same conclusion as the study on taxi drivers. In 2023, researchers ran a machine learning model on more than 22,500 people in a national dataset and were able to predict which ZIP codes had higher rates of Alzheimer’s with 84% accuracy based on how complex the environment was. Those living in spatially complex surroundings – the kind that force active map building, such as dense street networks with numerous intersections, diverse points of interest and landmarks, and multiple path options – were less likely to develop Alzheimer’s.

I would assume that the task of being a taxi driver would act as a near constant test for Alzheimer’s, would be interesting to do GWAS studies on older taxi drivers and compare against taxi drivers who quit earlier in their careers.

I guessed the probably died in a car accident or of something related to pollution exposure or being sedentary their entire adult lives.

I was going to make the same wisecrack, but in seriousness I assume they're counting elderly retired taxi drivers as taxi drivers even if they stopped working years before their deaths.

Yeah, that was the first thing that comes to mind.

And the second thing: What about modern taxi drivers that rely almost exclusively on GPS?

Alzheimers has a very long development stage compared to almost all other dementia (Lewis body also has a long timeline, but none of the other forms has anywhere close to the known length for Alzheimer’s disease). The original study article has no causal analysis, so a simple explanation is that super early Alzheimers symptoms (possibly even undetectable ones outside the context of intense taxi driving) drives people to abandon their taxi- or ambulance-driving jobs and seek other forms of employment.

Unless the arrow of causality is the other way: those that would tend to develop memory problems do not become or remain as Taxi drivers.

Not strange when you realize thinking is also physical.

Wouldn’t thinking be like exercise for the mind? And we know what happens to people that don’t exercise

Perhaps specific types of thinking cause somewhat sustained brain activity during waking hours that mitigates adverse physical changes leading to Alzheimer’s.

The opposite of this is how sleep and unconsciousness allows the brain to perform cerebrospinal fluid transfer based maintenance routines via the glymphatic system, and why sleep is important to neural health.

https://www.science.org/content/article/scientists-uncover-h...

n=1

No, it’s a licensed black cab thing. London has had mini cabs as well for many decades who didn’t need to study anything and were not even licensed till about 20 years ago. However, their downside is they have to be prebooked and can not be hailed on the street. Apps count as booking and not hailing I guess.

It seems common for taxi drivers to form a government-sanctioned cartel in order to limit the amount of competition. In the US this traditionally took the form of local taxi medallion systems, where there was a hard quota on how many taxis could be in the city. London's barrier to entry, unlike ours, at least guarantees a level of competence, even if it's excessive.

At least in the US, Uber and Lyft basically went around the taxi cartels. I'd assume that it wasn't easy for that to happen in Sweden though.

I’m sure Crazy Taxi provides the same benefits! :)

The thing about taxi drivers is that they have something at stake, while video games have no fail state effectively. You can be punished in-game, but overall it does not matter.

Also video games in general are pretty derivative, so playing the same genre probably won't help much after a certain point. But playing different ones can be very helpful, I imagine (same with other mediums).

Maybe when played at a high level. But too many games are too casual without much mental effort.

I mean, they should be. Games are for fun, not for work.

Age and life expectancy was controlled for in the study.

Half of people with Alzheimer's carry at least one APOE ε4 allele. However, a full quarter of the population carries that mutation, and most carriers never go on to develop Alzheimer's. Lifestyle matters a lot here.

This kind of misdirection is not helpful for educating people on changes they can make now to reduce their risk, rather than waiting for a silver bullet. Alzheimer's research is well-funded in the US as the octogenarians running our congress are personally invested in it.

I don't think "become a taxi driver" is a "quick lifestyle change".

Studies like this are useful inasmuch as they help us understand a disease more fully. Not sure what you mean by "misdirection"; the study's methodology seems sound?