Two jobs could protect you from developing dementia, according to a study.
Researchers found that taxi drivers and ambulance drivers are at a much lower risk of dying from Alzheimer's compared to over 400 different occupations.
This trend didn't hold for other transportation jobs that don't require navigating maps, like pilots or ship captains.
This led the team to believe that the mental exercise of planning a route in your head is particularly important in reducing Alzheimer's risk.
Their theory is that the hippocampus, the part of the brain that is crucial for memory, is the same part that's responsible for sense of direction and navigation.
Taxi and ambulance drivers have been shown in older studies to have particularly well-developed hippocampus', even as they age.
Study author Dr Anupam Jena, a physician at Massachusetts General Hospital said their results suggest: '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.'
About 7 million Americans currently live with Alzheimer's disease, and according to the Alzheimer's Association, that number is projected to continuing growing over the next decades to 13 million.
Because ambulance drivers have to constantly navigate new routes to the hospital, they're exercising a part of the brain called the hippocampus, which is responsible for spatial reasoning, memory and sense of direction.
Each grey dot represents a different occupation included in their study. They didn't report which occupations had the highest incidence of dementia. But those with the lowest included taxi drivers and ambulance drivers.
The new results were published in the British Medical Journal.
The team gathered data from the National Vital Statistics System of over 8.9 million people who died over 2020-2022 years.
Of those deaths, about 348,328 were attributed to Alzheimer's.
They looked at rates of the disease among 443 occupations, including bus drivers, aircraft pilots, ship captains and teachers.
They also accounted took into account factors like age, sex, race, ethnicity and level of education, and controlled for those demographics when analyzing the data.
They found on average, 3.88 percent of people included in the study died from Alzheimer's.
Within that Alzheimer's killed about 2.7 percent of ship captains and 4.5 percent of pilots, 1 percent of taxi drivers and 0.7 percent of ambulance drivers.
They didn't include information about which jobs has the highest amount of dementia diagnoses, nor did they give specific figures for each job. But according to their graphs, in some jobs, almost 8 percent of deaths were attributed to Alzheimer's disease.
Chief executives, one of the few roles they did include data for, ranked along the middle - with about 4 percent of these individuals dying from Alzheimer's.
The difference between the outcomes for the road-navigators versus other professionals in the transportation industry led the researchers to look towards one region of the brain: the hippocampus.
Older, influential research conducted by University College London examined the brains of taxi drivers after they had passed had found that this brain region, responsible for spatial reasoning and memory, was particularly robust in taxi drivers as compared to other professions.
As people age, the amount of healthy tissue in the brain naturally begins thinning. In Alzheimer's disease, this happens at a much faster rate, leading to the memory loss, personality changes and confusion often associated with the disease.
As people age, they naturally lose some volume of their brain tissue, which can be associated with some of the age-related changes some elderly people begin seeing.
But in Alzheimer's disease, the tissue disappears en masse, instead of in small, barely noticeable increments, like in normal age.
It could be that by constantly strengthening the connections in this part of the brain, taxi and ambulance drivers are making their brain more resilient to the process of Alzheimer's.
However, Dr Jena noted, it's difficult to say if the results they saw in the study are the result of the job itself. He said their paper should act as a jumping off point for further research, not as 'conclusive'.
Likewise, other scientists not involved in the study expressed doubt that these results mean that having a certain job can protect you from getting dementia.
Professor Tara Spires-Jones, the President of the British Neuroscience Association who wasn't involved in the research, said that scientists still can't conclude for certain that having certain jobs stops dementia from developing and that there may be other factors at play.
Prof Spires-Jones said: 'It is possible that people who are at higher risk of Alzheimer's may not choose memory intensive driving occupations.'
Professor Robert Howard, Professor of Old Age Psychiatry at University College London expressed similar doubt but offered a different explanation.
He said: '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.'