Scientists believe people who work in these two jobs have a lower risk of Alzheimer's
Taxi and ambulance drivers have lower death rates from Alzheimer’s than hundreds of other professions, pointing to a potential link between memory-intensive jobs and dementia risk, a new study has found.
These drivers must memorise entire city street networks with quick recall, and previous research in the UK indicates that London taxi drivers have functional changes to the hippocampus over decades of navigating the city.
The hippocampus is used for spatial memory and navigation, and it is also one of the first regions of the brain to be affected by Alzheimer’s disease, the most common form of dementia.
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For the new study, which was published in The BMJ, researchers from Harvard Medical School analysed Alzheimer’s death rates for nearly 9 million people who died in the US between 2020 and 2022.
They included 443 occupations, but focused specifically on bus drivers, airplane pilots, and ship captains in order to compare taxi and ambulance drivers with other transportation jobs that don’t require the same degree of memory-intensive navigational skills.
Navigational tasks might offer protection
In the general population, 1.69 per cent of all deaths were linked to Alzheimer’s, far higher than the 1.03 per cent for taxi drivers and chauffeurs and 0.91 per cent for ambulance drivers.
Meanwhile, the Alzheimer’s death rates for other transit jobs ranged from 1.65 per cent (bus drivers) to 2.34 (airplane pilots) when researchers adjusted for age at death, sex, race and ethnicity, and educational level.
"Our findings raise the possibility that frequent navigational and spatial processing tasks, as performed by taxi and ambulance drivers, might be associated with some protection against Alzheimer’s disease," the study authors said.
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Dr Anupam B Jena, a professor at Harvard Medical School and the study’s senior author, told Euronews Health that people should not stop using their GPS systems while driving as a way to stimulate their brains.
"The use of that part of the brain in taxi drivers is happening over decades and in a very particular and intense way – minute to minute on-the-fly navigational/spatial processing," Jena said.
The researchers also warned that the study does not prove causality. It’s also possible that people who are better at navigation and processing geographic information are more likely to become taxi and ambulance drivers, meaning they might be at a lower risk of Alzheimer’s regardless of their job.
Angela Bradshaw, director for research at Alzheimer Europe, told Euronews Health that the researchers are right to be cautious, but that the cognitive training required for “frequent spatial and navigational processing” could help curb the risk of dementia.
"There are a number of studies showing that cognitive stimulation can be beneficial," Bradshaw said, pointing to a 2023 study in Australia that found that participating in activities that stimulate the brain, such as taking classes, writing letters, or doing crossword puzzles, was associated with a lower risk of dementia over 10 years.
Study limitations
However, she noted that other factors make it difficult to "draw a direct line between profession, the skills involved in doing a particular job, and the risk of death from Alzheimer’s disease".
Independent researchers pointed to a few of those factors, including the fact that the taxi and ambulance drivers in the study died on average around ages 64 to 67, while Alzheimer’s onset is typically after age 65.
Further, few of the drivers were women, who are more likely to develop Alzheimer’s than men, and the analysis didn’t consider genetics or include scans that could show any changes to the brain as a result of their jobs.
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More research would be needed to determine whether the mental load associated with taxi and ambulance driving can actually protect against dementia, the study authors said.
Even with the limitations, though, the findings "highlight the need for more fundamental research into how to protect our brains from Alzheimer’s disease," Tara Spires-Jones, a dementia researcher and president of the British Neuroscience Association, said in a statement.
Nearly 8 million people in the European Union have dementia, with Alzheimer’s likely accounting for more than half of cases, according to Alzheimer Europe.
