Become a Taxi or Ambulance Driver to Avoid Dying of Alzheimer’s Disease?
Study finds careers that involve memory and spatial navigation seem to have lower incidences of Alzheimer’s disease
Back in 2000, a study of 16 London taxi drivers suggested that cabbies had positive changes in their hippocampus, the part of the brain involved with memory and navigation. The study was inspired by the fact that since 1865, London cabbies had to pass an enormously difficult test on the landmarks, streets and routes of the city called “the Knowledge.”
As it turns out, the hippocampus is the part of the brain most affected by Alzheimer’s disease. So Harvard researchers Christopher Worsham, Anupam Jena, Vishal Patel, Michael Liu and Joseph Newhouse wanted to evaluate the rates of Alzheimer’s deaths among taxi and ambulance drivers — people who generally depend upon memory and navigation. They used data that associates the death records of Americans to their occupations. The study also included bus drivers, ship captains, and aircraft pilots, believing that they tend to use set routes, so they expected fewer changes to the hippocampus. Their study was published in The BMJ.
The researchers studied the rate of death from Alzheimer’s disease associated with more than 400 occupations, with a particular focus on age of death. The two occupations with the lowest rate of Alzheimer’s death in the U.S.? Cab drivers and ambulance drivers — 56% lower than the general population.
These professions did not, however, have lower death rates from other types of dementias where the hippocampus isn’t as involved. The other “drivers,” i.e., bus drivers, airline pilots and ship captains, had Alzheimer’s death rates consistent with the general population.
In a TIME Magazine article written by Worsham and Jena, they note, “While striking, our study is unable to establish that driving a taxi itself causes reduces rates of death from Alzheimer’s disease — it simply establishes a link, albeit a highly curious one.”
Cause and effect can be tough to determine when it comes to disease, although sometimes it is clear, say tobacco use and cancer. And when you’re talking behaviors and disease, whether that’s driving a taxi or doing crossword puzzles, the associations become more ambiguous. As they point out, what comes first, the good memory to pass the Knowledge test, or the memory created from being a cab driver? And cab drivers typically have lower life expectancy than other professions.
It's yet another data point that suggests — and perhaps it is only “suggestive” — that actively using your brain in certain ways can decrease the risk of Alzheimer’s. Which isn’t to say that highly educated people who continue to think and learn aren’t at risk of Alzheimer’s. The authors of the TIME article note that “the human brain is ‘plastic’: it adapts to the demands placed on it, which is how we are able to learn. Could we also force our brains to make adaptations that lower the risk for Alzheimer’s disease?”
They make the suggestion that if we all stopped using GPS and relied on our memories, would that help stimulate the hippocampus? On a more personal note, I’ve noticed that a reliance on GPS instead of maps takes away from the spatial awareness of where you’re going and where you are at — that your brain uses maps to place things in context in a way that GPS does not. (Although, to be honest, I’m somewhat “directionally challenged” and can get lost even with a map).
Bottom line: Of the 8,972,221 people in their study who had died with occupational information, 3.88% had Alzheimer’s disease listed as the cause of death. Among taxi drivers, 1.03% died from Alzheimer’s disease and 0.74% of ambulance drivers died from Alzheimer’s disease (although it must be noted that in general, people in these professions seemed to die at a younger age on average, causing some data interpretation problems).
Conclusion: “Taxi drivers and ambulance drivers, occupations involving frequent navigational and spatial processing, had the lowest proportions of deaths attributed to Alzheimer’s disease of all occupations.”
It is less clear why that is, exactly, but it is interesting. Should you turn off your GPS?