Taxi and ambulance drivers are less likely than workers in almost any other profession to die from Alzheimer’s disease.
That was the surprising result of a 2024 study examining the death certificates of nearly 9 million people in the US.
Researchers think this has to do with their ability to navigate and interpret maps on the road, with experts offering their opinions all the mental work of real-time navigation while driving could do something good for the brain.
Of the 9 million death certificates from January 2020 through December 2022 that researchers examined, taxi and ambulance drivers had the lowest risk of dying from Alzheimer’s diseaseaffecting 7 million Americans, out of 443 occupations.
After adjusting for age, gender, race, ethnicity and education, about one in 100 taxi and ambulance drivers died of Alzheimer’s disease, compared with one in 60 people overall.
This pattern did not extend to other lanes, however, but leading researchers concluded that the key to reducing the risk of Alzheimer’s disease 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 depended on fixed or predetermined routes, such as bus drivers and airline pilots, did not appear to experience a similar benefit.
Researchers believe the association between navigational heavy work and a lower risk of Alzheimer’s disease centers on the hippocampus, a part of the brain that controls memory and spatial navigation.
Alzheimer’s disease is a form of dementia that affects 7 million Americans
It is one of the first areas of the brain to be damaged by Alzheimer’s disease: problems with spatial navigation and orientation are among the first signs of the disease, sometimes surfacing before obvious memory loss occurs.
In a groundbreaking 2000 study, neuroscientists compared the brains of licensed London taxi drivers with those of people who did not drive a taxi.
Their findings provided the first evidence through structural imaging that parts of the adult brain can measurably change under persistent navigational demand.
To earn a driver’s license, London taxi drivers 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 to complete.
The researchers found that London taxi drivers had measurably more gray matter in the posterior hippocampus, a brain region associated with storing large-scale spatial maps.
That volume was tracked with experience: the longer someone had driven, the larger that part of the brain.
The change comes about through practice and not through heredity. While people who are good at navigation may be attracted to this type of work, the work itself does have an impact on the brain.
The above graph shows the percentage of deaths from Alzheimer’s disease by occupation, with ambulance and taxi drivers showing some of the lowest figures
The above graph shows the percentage risk of dying from Alzheimer’s disease based on occupation, with ambulance and taxi drivers showing some of the lowest risk rates
Together, these two studies form a related case. Work that intensely trains the hippocampus can reshape it, and that reshaping could protect against one of the most feared diseases of aging.
Cartographers, urban planners, and geospatial analysts spend their workdays engaged in sustained spatial reasoning.
A geographic information systems (GIS) specialist may use a computer to overlay population data on flood exposure maps to determine who is at risk, or read satellite images to map land cover after a wildfire.
Researchers are juggling multiple layers of data, coordinating systems and scaling simultaneously.
Does spatial reasoning via a screen engage the hippocampus in the same way as moving through a real city?
While a taxi driver navigates from the inside at street level, GIS researchers imagine the space as a map from above – what cognitive scientists call allocentric reasoning.
However, these two perspectives overlap in the brain. The hippocampus also builds maps from external viewpoints, not just from the navigator’s own position.
Research into cognitive maps points towards the same conclusion as research into 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 with 84 percent accuracy which zip codes had a higher rate of Alzheimer’s, based on how complex the environment was.
Those who live in spatially complex environments—the kind that force active map building, such as a dense street network with numerous intersections, diverse sights and landmarks, and multiple path options—were less likely to develop Alzheimer’s disease.
The graph above shows the percentage of deaths from Alzheimer’s disease by occupation, among ambulance and taxi drivers, compared to other transport-related occupations
The above graph shows the percentage risk of dying from Alzheimer’s disease by occupation, among ambulance and taxi drivers, compared to other transport-related occupations
A follow-up study linked the geospatial complexity in a person’s environment to increased volume in the spatial navigation areas of the brain.
The researchers hypothesized that routinely building cognitive maps exercises the very circuits that Alzheimer’s disease first attacks. Repeatedly engaging the cognitive systems involved in spatial navigation may help slow disease symptoms.
However, these two studies focus on where people live, not on the work people do. Whether spatial reasoning via a screen uses the same circuitry as real-life city navigation has not yet been tested.
The implications of whether sustained spatial reasoning protects the brain extends beyond map makers and taxi drivers. Studies have repeatedly found a link between mentally complex occupations and delayed cognitive decline and a lower risk of dementia, even when education is taken into account.
Research into cognitive reserve – the brain’s ability to continue functioning despite illness – may help explain why two people with a similar burden of disease can exhibit markedly different levels of cognitive impairment.
If demanding spatial thinking protects the brain, then the way societies design schooling, vocational training, and retirement all become issues of brain health.
Spatial reasoning can be trained, and training options are already widespread. GIS and remote sensing instruction are available worldwide through geography, engineering, public health, and environmental science programs.
If sustained engagement in spatial reasoning can help the brain strengthen the circuits that Alzheimer’s disease first attacks, its value extends far beyond the technical skills it builds.
This article is adapted from The Conversation, a nonprofit news organization dedicated to sharing the knowledge of experts. It was written by Hatim Sharif, professor of civil and environmental engineering at the University of Texas at San Antonio. It was edited by Alexa Lardieri, the US health editor at the Daily Mail.
