Taxi drivers and ambulance drivers, whose jobs require frequent spatial and navigational processing, have the lowest levels of death due to Alzheimer's disease compared with other occupations, finds a study in the Christmas issue of The BMJ.
The findings are observational, so can't confirm a direct link, but the researchers say they raise the possibility that memory intensive driving occupations, such as taxi and ambulance driving, might be associated with some protection against Alzheimer's disease.
The hippocampus is a brain region used for spatial memory and navigation and has been shown to be enhanced in London taxi drivers compared with the general population.
It is also one of the brain regions involved in the development of Alzheimer's disease, raising the possibility that occupations that demand frequent spatial processing may be associated with decreased Alzheimer's disease mortality.
To investigate this, a team of US researchers analysed death certificates for adults from 443 different occupations between 1 January 2020 and 31 December 2022. Data included cause of death, usual occupation (in which the decedent spent most of their working life), and sociodemographic information (eg, age, sex, race, ethnic group, and educational attainment).
Of nearly 9 million people who had died with occupational information, 3.9% (348,328) had Alzheimer's disease listed as a cause of death. Of 16,658 taxi drivers, 171 (1.03%) died from Alzheimer's disease, while among ambulance drivers, the rate was 0.74% (10 of 1,348).
After adjusting for age at death and other sociodemographic factors, taxi and ambulance drivers had the lowest proportion of deaths from Alzheimer's disease of all occupations examined (1.03% and 0.91% respectively) and compared with the general population (1.69%).
The researchers note that this trend was not seen in other transport-related jobs such as bus drivers or aircraft pilots (possibly due to their reliance on predetermined routes) or with other forms of dementia, suggesting that neurological changes in the hippocampus or elsewhere amongst taxi and ambulance drivers may account for the reduction in Alzheimer's risk.
This is an observational study, so no firm conclusions can be drawn about cause and effect. And the authors acknowledge various limitations, including that individuals who are at higher risk of developing Alzheimer's disease may be less likely to enter or remain in memory intensive driving occupations such as taxi and ambulance driving. However, they say this is unlikely given that Alzheimer's disease symptoms typically develop after working age.
"We view these findings not as conclusive, but as hypothesis generating," they say.
"Further research is necessary to definitively conclude whether the spatial cognitive work required for these occupations affect risk of death from Alzheimer's disease and whether any cognitive activities can be potentially preventive."
