Walking around the city may protect the brain from Alzheimer's disease

Taxi and ambulance drivers in the US demonstrated the lowest risk of death from Alzheimer's disease among 443 professions analyzed in a 2024 study. This fact attracted attention because these specialists spend most of their work on orientation, route calculation, and updating mental maps.

According to Hatim Sharif, a professor of civil and environmental engineering at the University of Texas in San Antonio, the results suggest that constant efforts to interpret space may stimulate brain areas related to memory and navigation. Researchers studied nearly 9 million death certificates registered in the US from January 2020 to December 2022.

After accounting for age, gender, ethnicity, and education level, a difference was identified: approximately 1 in every 100 taxi and ambulance drivers died from Alzheimer's disease, compared to 1 in every 60 people in the overall analyzed group. A similar advantage was not observed in other drivers.

A possible explanation lies in the type of activity performed. Taxis and ambulances require real-time navigational decision-making, whereas other professions follow fixed or predetermined routes. The hippocampus is central to this discussion, as this area is involved in memory and spatial orientation and is one of the first areas affected by Alzheimer's disease. Difficulty finding paths can arise even before obvious memory problems appear.

Sharif noted that he has worked with digital maps and geographic information systems for over two decades. He previously hypothesized that spatial thinking across map layers was purely professional. An earlier 2000 study already found similar signs. Scientists compared the brains of licensed London taxi drivers with the brains of people who did not drive taxis.

To get a license, one had to memorize more than 25,000 streets within a 10-kilometer radius of Charing Cross. This challenge, known as 'The Knowledge,' took an average of three to four years. Taxi drivers showed more gray matter in the posterior hippocampus. A link with experience was also found: the longer a person drove in the city, the larger this brain area was. The change was linked to practice, not innate characteristics.

This issue is also interesting to cartographers, urban planners, and geospatial analysts. When working with GIS, these specialists correlate different data layers, coordinates, and scales to understand the relationships between places. Among such activities is navigation within the environment, unlike a GIS specialist who observes space through a map. It is not yet clear whether these two experiences activate the same brain circuits.

A 2023 study analyzed over 22,500 people and was able to predict with 84% accuracy which postal codes have a higher incidence of Alzheimer's disease by using environmental complexity. Areas with dense street construction, many intersections, landmarks, and numerous route options were associated with a lower probability of developing the disease.

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The idea is also related to the concept of cognitive reserve, which refers to the brain's ability to continue functioning despite changes caused by the disease. Spatial thinking can be trained, and opportunities for such learning are widespread. According to Hatim Sharif, geography, engineering, public health, and ecology courses already use GIS and remote sensing. However, it remains unknown whether this exercise can truly strengthen the brain circuits that are first affected by Alzheimer's disease.