Air pollution might be associated with the development of Alzheimer's disease.

The possible link was recently revealed in two studies.

The first, published in The Lancet magazine, reports results from a Canadian team who studied the possible relationship between developing Alzheimer’s and the particular geographical area one lives in.
And it discovered an interesting correlation...

The team used postal codes to track approximately 6.6 million Ontario citizens for more than a decade.
It then demonstrated that the dementia rate of people who lived within 50 meters of main roads was 12% higher than those who lived 200 meters away from them.

The number seems small, but it is highly significant.
It suggests that one case of Alzheimer out of ten is related to living near a main thoroughfare.

It is, however, too early to say whether air pollution from vehicles is behind this result. As the authors of the paper noted, noise and stress caused by the proximity of homes roads might also have a role to play in the correlation the Canadian team found.

That said, the second study suggests a more direct link between air pollution and Alzheimer’s disease.

Published in Translational Psychiatry, this 11-year epidemiological study reports twice as many cases of Alzheimer’s amongst those who had been exposed to high levels of ultrafine air particles during their lives.

It is nevertheless still unclear how air pollution could cause the disease.

However, scientists do know that small particles, those smaller than 200 nanometers, can directly enter the brain of rodents and cause inflammation. The current hypothesis is that this same mechanism would trigger the disease in humans.

Further studies are required to confirm this hypothesis and to ensure that small air particles really can trigger Alzheimer's disease.