December 16, 2024

expert reaction to study reporting lower Alzheimer’s deaths in certain professions (taxi drivers and ambulance drivers)

A study published in The BMJ looks at Alzheimer’s disease mortality among taxi and ambulance drivers.

Dr Richard Oakley, Associate Director of Research and Innovation at Alzheimer’s Society, said:

“This new observational study suggests that taxi and ambulance drivers, whose jobs rely on spatial memory, have a lower risk of developing Alzheimer’s disease. 

“This is an interesting theory as the hippocampus, the brain region used for spatial memory and navigation, is one of the first that Alzheimer’s affects. 

“However, the results are not supported by scans to show changes in the brain. It also overlooks that some people hold multiple jobs in their lifetime, and it doesn’t consider biological or social factors, such as genetics or socio-economic status, which could affect a person’s chances of developing Alzheimer’s disease, so it is difficult to draw any firm conclusions.  

“We know that everyone has a risk of developing dementia and this varies between individuals. The Lancet Commission on Dementia, part-funded by Alzheimer’s Society, suggests that nearly half of dementia cases across the world could be delayed or prevented.  

“Some dementia risk factors cannot be reduced or avoided, but many others can. These include excessive alcohol consumption, lack of physical activity, smoking and limited social contact among others. We can all take steps to reduce our risk.” 

Prof Tara Spires-Jones, Director of the Centre for Discovery Brain Sciences at the University of Edinburgh, Group Leader in the UK Dementia Research Institute, and President of the British Neuroscience Association said:

“This paper by Patel and colleagues examined data from over 8 million people in the US finding that taxi and ambulance drives had lower proportions of death attributed to Alzheimer’s disease than people with other jobs. This is a large study that adds to knowledge around building brain resilience to reduce the risk of Alzheimer’s disease. However, it is not possible from this type of data to conclude for certain that these occupations protect people from Alzheimer’s disease.  It is possible that people who are at higher risk of Alzheimer’s may not choose memory intensive driving occupations, which is a so-called “selection bias”.  It is also worth noting that 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. This is a serious limitation of the study as 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. Similarly, the proportion of women taxi and ambulance drivers was 10-22% whereas in all other occupations this was 48%.  This is important because women are more likely to develop Alzheimer’s disease than men.  Authors used statistics to try and take into account these limitations, but they do limit the interpretation of the study.  Even with these limitations, the data in the study are interesting and highlight the need for more fundamental research into how to protect our brains from Alzheimer’s disease.”

Prof Robert Howard, Professor of Old Age Psychiatry, UCL Division of Psychiatry, UCL, said:

“The authors of this interesting study are correct to be cautious about claiming that the navigational effort involved in their occupation protected taxi and ambulance drivers from Alzheimer’s disease. It is just as likely that individuals with better navigational and spatial skills flourish in these jobs and this represents the presence of greater cognitive reserve so that they need more neurodegeneration before they develop symptoms of Alzheimer’s disease. Of course, the advent of satnav technology, with less reliance on inherent navigational abilities, is likely to reduce any such effects. Meanwhile, it would be premature to suggest that drivers should turn off their satnavs to prevent the development of dementia.”

‘Alzheimer’s disease mortality among taxi and ambulance drivers: population based cross sectional study’ by Vishal R Patel et al. was published in The BMJ at 23:30 UK time on Monday 16^th December.

DOI: https://dx.doi.org/10.1136/bmj-2024-082194

Declared interests

Prof Tara Spires-Jones: I have no conflicts with this study but have received payments for consulting, scientific talks, or collaborative research over the past 10 years from AbbVie, Sanofi, Merck, Scottish Brain Sciences, Jay Therapeutics, Cognition Therapeutics, Ono, and Eisai. I am also Charity trustee for the British Neuroscience Association and the Guarantors of Brain and serve as scientific advisor to several charities and non-profit institutions.

Prof Robert Howard: No COI

For all other experts, no reply to our request for DOIs was received.