Can a job protect you from Alzheimer’s? Researchers find two that may

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Researchers at Harvard Medical School have crunched the numbers in almost 9 million U.S. death certificates issued between 2020 and 2022, looking for links between occupations and Alzheimer’s as a cause of death. It seems there may be a benefit to being on the road.

Of nearly 9 million million people with certificates listing occupation in the U.S. National Vital Statistics System, 3.88 per cent had Alzheimer’s disease listed as a cause of death, amounting to some 348,328 people.

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However, only 1.03 per cent of taxi drivers and just 0.74 per cent of ambulance drivers died from Alzheimer’s disease, according to the research, which was led by Dr. Anupam Jena of Harvard Medical School and Massachusetts General Hospital in Boston.

The connection seems intuitive. These types of jobs require the brain to create and reference spatial maps. In fact, research from the turn of the century found that London taxi drivers showed physical changes in their brains compared to others who were similar in age, education, and intelligence. More recent studies have even shown differences in the brains of new taxi drivers before and after preparing for a rigorous test of their recall of London streets, a body of data known as “The Knowledge.”

“The same part of the brain that’s involved in creating cognitive spatial maps — which we use to navigate the world around us — is also involved in the development of Alzheimer’s disease,” said Dr. Vishal Patel, another of the study’s authors and a resident physician in the Department of Surgery at Brigham and Women’s Hospital.

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“We hypothesized that occupations such as taxi driving and ambulance driving, which demand real-time spatial and navigational processing, might be associated with a reduced burden of Alzheimer’s disease mortality compared with other occupations.”

Jena added: “Our results highlight the possibility that neurological changes in the hippocampus or elsewhere among taxi and ambulance drivers may account for the lower rates of Alzheimer’s disease.”

Still, he cautioned against reading too much into the study. “We view these findings not as conclusive, but as hypothesis-generating,” he said. “But they suggest that it’s important to consider how occupations may affect risk of death from Alzheimer’s disease and whether any cognitive activities can be potentially preventive.”

Other types of dementia such as vascular dementia — caused by impaired blood flow to the brain — didn’t show the same relationship as Alzheimer’s disease, the study found.

And other transportation-related jobs that didn’t require as much real-time spatial and navigational processing didn’t have the same results as taxi or ambulance drivers. Bus drivers, for example, ranked 263rd in the list. And ship captains and aircraft pilots were among the highest in terms of risk of dying from the disease.

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It’s also worth noting that other factors could be at play.

“The age at death of taxi and ambulance drivers in this study was around 64-67 years of age, while for all other occupations this was 74 years of age,” University of Edinburgh neuroscientist Tara Spires-Jones noted in reaction to the study. “The age of onset of Alzheimer’s is typically after 65 years old, meaning that the taxi and ambulance drivers might have gone on to develop Alzheimer’s if they lived longer.”

She also pointed out that women are less likely than men to be taxi drivers and ambulance drivers (10 to 22 per cent) compared to all other occupations (48 per cent). “This is important because women are more likely to develop Alzheimer’s disease than men,” she said.

It’s also possible that people who are predisposed to Alzheimer’s disease may avoid memory-intensive jobs in the first place, or that some of the study subjects spent relatively little time in their “main” occupation, perhaps starting it later in life.

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