A recent study published in Neurology, a journal of the American Academy of Neurology, suggests a correlation between traffic-related air pollution—such as that found in Alabama, Indiana, and similar regions—and the onset of Alzheimer’s disease.
The research found that people exposed to fine particulate matter (PM 2.5) amyloid plaques, an indicator of Alzheimer’s, in their brains are more prone to developing the condition.
Although the study does not conclusively establish causation, it contributes to the growing body of evidence hinting at a potential environmental link to this debilitating disease.
This suggests that residents of the Top 10 most polluted areas in the U.S.—including Birmingham, Atlanta, central Pennsylvania, Los Angeles, Houston, St. Louis, Indianapolis, the Chicago area, Northwest Indiana, and Bakersfield—may face heightened risks.
Additionally, age plays an important role, particularly for anyone nearing their mid-70s, as the average age of the participants in this study, whose brains were donated, was 76.
Researchers also explored whether possessing the main gene variant associated with Alzheimer’s disease, APOE e4, influenced the relationship between air pollution and Alzheimer’s markers. They discovered that the strongest association between air pollution and Alzheimer’s markers was observed among those without the gene variant.
Apart from relocating to regions like Maine or Vermont or minimizing outdoor activities, a separate study from the University of Michigan School of Public Health suggests that Alzheimer’s and dementia might not solely be linked to inhaling highway exhaust fumes.
Environmental factors such as pollutants from agricultural applications, wildfires, and gas stations could also be contributing factors. For example, wildfires, due to their extensive reach, are estimated to account for up to 25% of fine particulate matter exposures nationwide over the course of a year, with figures reaching as high as 50% in certain western regions of the country.
The authors of the study added: “These results add to the evidence that fine particulate matter from traffic-related air pollution affects the amount of amyloid plaque in the brain. This suggests that environmental factors such as air pollution could be a contributing factor to Alzheimer’s in patients in which the disease cannot be explained by genetics. More research is needed to investigate the mechanisms behind this link. ”
