A study by scientists affiliated with Harvard University and published in the journal The BMJ has found that transportation workers — particularly taxi drivers and ambulance drivers — recorded the smallest proportion of deaths attributed to Alzheimer's disease among 443 occupations examined, UOL reports. The researchers reached the finding after reviewing nearly 9 million death records from the United States covering the years 2020 to 2022.
After statistical adjustments, ambulance drivers showed an Alzheimer's death proportion of 0.91%, while taxi drivers stood at 1.03%. Across the full population studied, the adjusted figure was 1.69%.
Why it matters
Alzheimer's is a progressive disease that erodes memory and orientation, and the hippocampus — a brain region central to both — is among the earliest areas affected. If the demands of certain jobs genuinely influence that region over a working life, the finding could sharpen understanding of how daily mental effort relates to brain health. The study's authors, however, did not establish that these drivers are less likely to develop the disease; they measured the share of deaths attributed to it.
What the numbers showed
The results were not uniform across transport work. Bus drivers recorded 1.65%, boat captains 2.12% and airplane pilots 2.34%. Pilots placed fourth among the 443 occupations with the highest Alzheimer's death proportions.
The researchers drew a distinction they considered significant: taxi and ambulance drivers must make frequent decisions about which route to take, while the other transport professionals generally follow set routes. The leading hypothesis centers on the hippocampus, which handles memory and spatial navigation.
Gustavo Omena, a psychiatrist and psychogeriatric specialist, explained to UOL how the mental map works. When a person thinks through a route, he said, they draw on recollections, identify landmarks and relate their own position to the destination — effectively building a mental picture of the city. The need to alter course because of traffic jams, road closures or unfamiliar destinations, he said, demands a different kind of effort than repeating the same trip each day. The authors' hypothesis, according to Omena, is that constructing varied routes in real time differs from retracing a known one.
Raphael Boechat, a psychiatrist and professor at the UNICEPLAC medical school, pointed to sustained concentration as another possible factor. These jobs, he told UOL, require constant focus — especially for ambulance drivers, who must make quick decisions amid unexpected situations. A sudden braking or a pedestrian stepping into the road forces a driver to redirect attention rapidly, engaging different brain functions, he said.
Earlier evidence from London, and reasons for caution
The link between the profession and spatial memory had been studied before in London. In 2011, researchers at University College London followed candidates for taxi licenses as they prepared for the qualification. Driving the city's traditional black cabs requires memorizing thousands of streets and landmarks, and the training — known as The Knowledge — can take three to four years. Comparing scans taken before and after the course, the researchers found growth in gray matter in a part of the hippocampus among candidates who passed. Neither those who failed nor a control group showed the same change.
Omena described this as evidence of neuroplasticity — the brain's capacity to change through experience and learning — but stressed that a shift in the volume of a brain region does not by itself mean protection against Alzheimer's. He also urged restraint in reading the American study. Because it examined death records, it identified a lower proportion of deaths from the disease but did not prove that taxi drivers are less likely to develop it. Other influences, he noted, could shape the results: health conditions, differences in life expectancy, and even the possibility that people with stronger spatial orientation are more likely to stay in these jobs.
A driver's own experience
Francisco Moreno, a taxi driver since the 1980s, told UOL he long kept streets, routes and shortcuts in his head, and for much of his career finding the best way depended on his own recall. Then navigation apps became part of his routine. After a stretch of using Waze often, he noticed that some trips he once handled without effort had become harder. In his view, the ease of following the app's instructions had cut into his habit of working out routes himself. He now prefers to drive without GPS when he knows the destination and traffic is not a concern.
His memory has become a family joke, he said — relatives ask him to recall events and details, including things younger family members have forgotten. Until speaking with UOL, he had never considered that his work might be connected to that ability.
Boechat said the findings underscore the value of keeping the brain active throughout life. Mariana Lino, a neurologist, offered a related nuance: navigation apps can shift part of the orienting work to the device, and there is a difference between merely following instructions and trying to memorize landmarks, understand the surroundings and plan a route. She stressed that using GPS does not harm the brain or raise Alzheimer's risk.
What to watch: whether future research moves beyond death records to track Alzheimer's diagnoses among drivers over time, which would test the hippocampus hypothesis more directly.
