Taxi and ambulance drivers are less likely than workers in almost any other job to die of Alzheimer’s disease. That was the surprising result of a 2024 study examining the death certificates of nearly 9 million people in the U.S.
These findings stopped me in my tracks because those two jobs rely on the same thing as my own work: maps. I have spent more than two decades staring at maps — digital ones with multiple layers: flood boundaries draped over census blocks, car crash hot spots plotted against road geometry, and satellite readings of rainfall stitched across river basins.
Taxi driver brains
Of the 9 million death certificates from January 2020 to December 2022 that researchers examined, taxi and ambulance drivers had the lowest risk of dying from Alzheimer’s disease out of 443 occupations. 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.
This pattern did not extend to other driving jobs. The researchers concluded that the key to reducing the risk of Alzheimer’s was not driving itself but continuous real-time navigation: the constant work of locating yourself in space, tracking a destination and updating a mental map as conditions change. Drivers whose jobs relied on fixed or predetermined routes, like bus drivers and aircraft pilots, didn’t seem to experience a similar advantage.
Researchers believe the association between navigation-heavy work and lower Alzheimer’s risk centers on the hippocampus, a part of the brain that governs memory and spatial navigation. It’s one of the first brain regions that Alzheimer’s damages: Problems with spatial navigation and orientation are among the earliest signs of the disease, sometimes surfacing before obvious memory loss.
In one landmark 2000 study, neuroscientists compared the brains of licensed London taxi drivers with those of people who did not drive cabs. Their findings provided the first evidence that regions of the adult brain can measurably change under sustained navigational demand. To earn a license, London cabbies must memorize more than 25,000 streets within a 6-mile radius of Charing Cross, a challenge known as “The Knowledge” that takes three to four years.
The researchers found that London taxi drivers had measurably more gray matter in the posterior hippocampus, a brain area tied to storing large-scale spatial maps. That volume tracked with experience: The longer someone had driven, the larger that part of the brain.
Where map specialists fit in
Cartographers, urban planners and geospatial analysts spend their working days in sustained spatial reasoning. Does spatial reasoning through a screen engage the hippocampus the way moving through a real city does? While a taxi driver navigates from inside the scene at street level, GIS researchers picture space from above as a map — what cognitive scientists call allocentric reasoning. But these two perspectives overlap in the brain.
Research on cognitive maps points toward the same conclusion. In 2023, researchers ran a machine learning model on more than 22,500 people 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 — were less likely to develop Alzheimer’s.
Protecting your brain
The implications of whether sustained spatial reasoning protects the brain reach beyond mapmakers and cab drivers. Studies have repeatedly found a link between mentally complex occupations and delayed cognitive decline and lower dementia risk, even after accounting for education.
Research on cognitive reserve — the brain’s capacity to continue functioning despite disease — can help explain why two people with a similar disease burden can show markedly different levels of cognitive impairment. If demanding spatial thinking protects the brain, then how societies design schooling, professional training and retirement all become questions of brain health.
Spatial reasoning can be trained, and training opportunities are already widespread. If sustained engagement with spatial reasoning can help the brain strengthen the circuitry that Alzheimer’s attacks first, its value reaches well beyond the technical skills it builds.
This article is republished from The Conversation under a Creative Commons Attribution-NoDerivatives 4.0 International License.