Taxi and ambulance drivers 'at lowest risk of dying from Alzheimer's disease'

People who have to regularly visualise routes, like taxi and ambulance drivers, may be at lower risk of dying from Alzheimer’s, a new study has found. The same area of the brain used to create cognitive spatial maps is known to be involved in the development of Alzheimer’s disease.

Researchers wondered if that meant taxi drivers and others with similar jobs would be at lower risk. So researchers analysed death data for adults with 443 occupations, also studying their age, sex, race, ethnicity and educational attainment.

In total, 3.88 per cent of the nine million people included in the study died of Alzheimer’s. But among taxi drivers it was just 1.03 per cent. It was even lower for ambulance drivers at 0.91 per cent.

The trend was not found in other transportation-related jobs. Bus drivers had a 3.11 per cent death rate and aircraft pilots had a 4.57 per cent death rate, with both jobs less reliant on mapping routes in real time. “Notably, deaths from underlying cause of Alzheimer’s disease were lower for taxi and ambulance drivers than for other occupations with a similar mean age at death,” said the report.

Alzheimer's disease is the most common form of dementia, which affects about 55 million people worldwide, most of them aged 65 or older. There is no cure, although drugs can treat symptoms such as memory problems and confusion.

The new report said “ambulance and taxi drivers consistently had the lowest proportional Alzheimer’s disease mortality" among those who died aged 60 years or older and when Alzheimer’s disease was specified as either an underlying or contributing cause of death.

“The pattern of lower Alzheimer’s disease mortality was not observed in other occupations related to transportation with fewer navigational demands. For instance, aircraft pilots and ship captains ranked as having the fourth and 23rd-highest adjusted Alzheimer’s disease mortality, out of 443 occupations, while bus drivers ranked 263rd," it added.

Senior author Dr Anupam B Jena, a physician in the Department of Medicine at Massachusetts General Hospital, said the results suggest that neurological changes in the hippocampus or elsewhere among taxi and ambulance drivers may account for the lower rates of Alzheimer’s disease.

The trend was not seen in other types of dementia, suggesting the possibility that the changes they experienced in the hippocampus lowered their risk of Alzheimer’s specifically, said the report. But researchers said because it is an observational study, no conclusions can be drawn about cause and effect.

“We view these findings not as conclusive, but as hypothesis-generating. 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.”

In August, researchers revealed that they had found a "very encouraging" way of taming Alzheimer’s disease in mice, after a protein drug "completely suppressed" the effects of a harmful molecule called amyloid beta. Another study from the same month found that new risk factors contributing towards Alzheimer’s disease suggest neurodegeneration and dementia may not be an inevitable sign of ageing, with lifestyle choices playing an even greater role than first thought.

Half of all dementia cases resulted from 14 lifestyle and environmental factors that can be altered to cut the risk of disease, say researchers. Contributing factors towards dementia include brain injury, social isolation, depression, hearing loss and air pollution, as well as modifiable lifestyle factors like obesity, high blood pressure, diabetes, smoking, alcohol and sedentary living. Raised cholesterol, high red meat consumption and sight loss were also recently added.