from Hacker News

Taxi drivers offer a clue to Alzheimer's risk

by julienchastang on 12/24/24, 4:23 PM with 109 comments

  • by neonate on 12/27/24, 7:06 PM

  • by noduerme on 12/27/24, 10:16 PM

    A study came out in 2000, back when I was driving a taxi, showing that London cabbies with "the Knowledge" had changes to their brain anatomy.[0]

    My girlfriend at the time spotted it in a college course and showed it to me. I remember her joking that she was only with me for the size of my hippocampus.

    I would hypothesize that it's more related to spacial/geographic memory than simply navigating spaces one visually perceives. My guess is the effect would be much less pronounced in people who drive for a living now relying on GPS maps.

    London taxi drivers, apparently, still must pass the notoriously difficult Knowledge test.[1] A similar (but less rigorous) test was required for Los Angeles cab drivers when I drove. And of course, if you weren't familiar with the street where your next call was (or where your passenger wanted to go), you had only seconds at a red light to leaf through the enormous Thomas Guide and memorize how you would get there.[2]

    [0] https://www.pnas.org/doi/full/10.1073/pnas.070039597

    [1] https://london-taxi.co.uk/the-knowledge/

    [2] https://archive.org/details/losangelescounty0000thom/page/n9...

  • by apsec112 on 12/27/24, 7:23 PM

    Here's a link to the actual study, which is very readable:

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

  • by phillypham on 12/27/24, 8:02 PM

    I wonder if this also applies to people that live urban environments that don't drive and have to navigate walking or using the subway.

    From my anecdotal evidence, it does seem that the average elderly person in NYC is way more active and social than an elderly person in the suburbs. But of course, it could be that people that live in cities self-select.

  • by zerr on 12/27/24, 7:31 PM

    Does navigating spaghetti code count as well?

  • by daedrdev on 12/27/24, 9:15 PM

    I do wonder though if its cause and effect are the wrong way.

    Perhaps the type of person who can remember enough to get the job and be good at it is already less likely to get Alzheimers, and we just selected for those people.

    I think this is not very likely though

  • by this_steve_j on 1/8/25, 12:09 AM

    Recently related:

    Herpes virus and repeated head trauma linked to Alzheimer’s, study finds (2025) https://news.ycombinator.com/item?id=42629076

    Why Alzheimer's Scientists Are Re-Thinking the Amyloid Hypothesis (2025) https://news.ycombinator.com/item?id=42628529

    Herpes Virus Might Drive Alzheimer's Pathology, Study Suggests (2025) https://news.ycombinator.com/item?id=42578383

  • by andsoitis on 12/27/24, 7:21 PM

    > Taxi drivers may have a lower risk of developing Alzheimer’s because they are constantly using navigational and spatial processing.

    It would be interesting to know whether certain kinds of video game play have a similar effect. On the one hand, you don’t do it for 8+ hours a day every day (unlike cab drivers), but on the other hand, there might be a much higher volume of spatial and navigational decisions packed per minute in certain games.

  • by DoingIsLearning on 12/27/24, 10:44 PM

    Am I interpreting the data correctly in that, whatever protective effect was found on Taxi drivers and Ambulance drivers, was actually aggravated on Ship Captains and Airline Pilots?

    My immediate thought went to the negative effect of sleep quality and work schedules, but I would expect the same sleep strain/stress for Ambulance drivers. A lot going on epidemiology wise but interesting study nevertheless.

  • by bgun on 12/27/24, 7:56 PM

    This is basic "mind palace" theory, no? Human memory is linked to navigation; the more you associate memories with navigable places, the stronger your memories will remain.

  • by thenerdhead on 12/28/24, 1:22 AM

    This reporting feels a bit superficial, especially given the exciting direction Alzheimer’s research is taking.

    It might sound unconventional, but what if taxi drivers, through constant exposure to small amounts of pathogens from travelers worldwide, experience enough immune imprinting to help prevent diseases like Alzheimer’s?

    There’s an intriguing study suggesting that one type of Alzheimer’s might be linked to a chronic gut infection that eventually makes its way to the brain.

    https://news.asu.edu/20241219-health-and-medicine-surprising...

    We are likely on the verge of a scientific revolution that will redefine viruses as key drivers behind some of the most devastating diseases known to humanity.

  • by ShakataGaNai on 12/27/24, 8:30 PM

    When I read these headlines I wonder "Causation? Correlation?". Maybe it's addressed in the study but.....

    Is it that navigating with you brain is good to prevent Alzheimers? Or are you just more likely to die from something else as a cabbie. Statically speaking your more likely to die, than average, from a traffic related accident. Maybe the all the fumes cause something else terrible that kills you, etc.

    It does seem logical to me that using your brain more could help offset these dementia related diseases. But it also seems like if that made a huge difference, we'd see statistically vastly more alzheimers in "low thought" jobs like retail cashiers and people who don't work/retire early vs say... collegiate professors.

  • by throw0101d on 12/27/24, 7:35 PM

    > Taxi drivers may have a lower risk of developing Alzheimer’s because they are constantly using navigational and spatial processing.

    A good reason to not use GPS/GNSS apps too much.

    Unless it's going to a location that's completely unfamiliar, I try to only check for red zones before I leave, and then use my familiarity of my city to get to my destination: know my starting point, know a major intersection near the destination, and avoid known-bad locations in between. If I get lost I can always pull out the app to re-orient.

  • by j7ake on 12/27/24, 7:40 PM

    A whole generation now uses navigation, is the prediction that there will be an increase in Alzheimer’s in this new generation due to reduced navigational processing?

  • by m3kw9 on 12/27/24, 7:25 PM

    Not sure how that compares to era where most people didn’t use google maps, but if you use google maps, you are using some part of your brain less especially memorizing or trying to reverse a route from memory. Or that if you can’t remember very well, you wouldn’t last long as a taxi driver(survivor ship bias)

  • by sys32768 on 12/27/24, 10:01 PM

    Did this study identify who had the APOE4 gene?

    Another study https://www.nature.com/articles/s41590-023-01627-6 suggests the APOE4 gene may be preventing immune cells in the brain from switching to the defensive "clean" mode.

    I know my mother's hippocampus was smaller than something like 94% of people her age when she was diagnosed 11 years ago.

    First signs of AD generally show up in the hippocampus.

    Maybe with heavy spatial reasoning activity in that region, the AD mechanism is stunted or interfered with.

    I would be curious to know what activities outside of vehicle navigation stimulate the hippocampus equally. I still play a lot of 3D video games.

  • by forgingahead on 12/28/24, 3:50 AM

    I remember a study as well where folks who were much more religious also had a lower rate of Alzheimer's. The purported cause was that remembering the hymns/chanting verses forces your brain to be more supple and active, staving off whatever causes it. Will try find it and link later.

  • by lupire on 12/27/24, 8:33 PM

    The study also shows that taxi drivers have very low lifespan, which of course is highly correlated to ower risk of death by Alzheimer's. They also ignored may other professions with similar or lower Alzheimer's risk.

    Overall, it feels suspicious that they ignored other potential explanations for the data.

  • by IAmGraydon on 12/27/24, 11:26 PM

    Does anyone know how to download the data for the charts in the study?

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

    The last one (9/9) has a download link, but none of the others do.

  • by yieldcrv on 12/27/24, 11:33 PM

    As said the last time this was posted

    Its because taxi drivers with Alzheimer's will get complained about and ousted from the profession before their death

    Meaning there are no cognitive benefits to extrapolate from this reality of using your brain, from this study

  • by byyoung3 on 12/27/24, 8:08 PM

    also probably higher rates of social interaction

  • by mewpmewp2 on 12/27/24, 9:37 PM

    I would be really interested in seeing an easily sortable and queriable dataset where you can sort also different causes of death and order them by all professions.

  • by scotty79 on 12/28/24, 2:07 AM

    I guess it might be hard to keep being a taxi driver when your brain gradually subsymptomatically deteriorates because of illness that will eventually kill you.

  • by kacesensitive on 12/28/24, 12:18 AM

    Or taxi drivers with Alzheimer's get fired or quit

  • by brcmthrowaway on 12/27/24, 11:30 PM

    Does this control for taxi driver ethnicity?

  • by whimsicalism on 12/28/24, 3:25 AM

    Could we just be seeing selection effects for very early indicators of alzehimers?

  • by iJohnDoe on 12/27/24, 7:18 PM

    Maze Runner premise? Stimulate brain activity.

  • by wigster on 12/27/24, 7:25 PM

    so - switch off your sat nav

  • by 7e on 12/28/24, 2:17 AM

    My DoorDash drivers can barely tie their own shoes. So yes, probably something to this.

  • by Unbefleckt on 12/28/24, 6:36 PM

    My Partner has absolute dogshit spatial memory. I visit a city once and I remember my bearings instinctively, probably due to playing a lot of badly designed mazelike Video games, but she can visit a City several times and still get lost going somewhere she has been before. Should we be worried?

  • by aeternum on 12/27/24, 7:43 PM

    Very flawed study. Looked at profession based on death certificate which is most recent profession.

    Those with Alzheimer's likely won't last long as taxi drivers so they find a new profession. And voila their profession from the viewpoint of this study is no longer taxi driver.

    Much surprise that our lauded peer review process didn't catch this.