Ambient Air Pollution and Alzheimer's

"This suggests that environmental factors like air pollution could be a contributing factor to Alzheimer's disease, especially in patients in which the disease cannot be explained by genetics."

"Donors who lived in areas with particularly high levels of traffic-related air pollution showed more plaques related to Alzheimer's disease at death than donors who lived in areas with lower air pollution concentrations." 

"In our study we used air pollution models, which can give us an estimate of the residential traffic-related air pollution concentration with a very fine resolution up to 200 to 250 meters. Of course you would see the highest levels of these pollutants around major highways, so people who lived very close to major highways had the highest exposure to traffic-related pollutants."

Anke Huels, assistant professor, Emory University, School of Public Health 

Rollins School of Public Health, Emory University

 Recently published in the journal Neurology, a new study on the association between ambient air pollution concentrations and signs of Alzheimer's disease in the brain, led to the conclusion that people exposed to higher concentrations of fine particulate matter [air pollution; PM2.5] a year before death were likelier to have higher levels of plaques [abnormally high clusters of protein fragments accumulated between nerve cells, a sign of Alzheimer's present in brain tissue].

 

It has long been accepted by experts in the field that PM2.5 concentrations are capable of triggering short-term respiratory problems. The particulate matter is minuscule -- measuring 2.5 microns and even less in diameter, enabling them to enter the bloodstream following inhalation. Breathing smoke also can irritate sinuses, throat and eyes, according to the Centers for Disease Control and Prevention.
Severe exposure can also link to heart attacks, stroke, lung cancer and cognitive function damage.

A strong association was also found between the pollution and dementia in people not genetically predisposed to Alzheimer's. The study found an association between exposure to specific kinds of pollution and signs of the disease, but it does not provide evidence that Alzheimer's disease is caused by air pollution. Tissue from 224 donors in the Atlanta metropolitan area who had donated their brains to research formed the base of the study.

What the study results did clarify for the researchers was that exposure to high levels of pollution increases the risk of Alzheimer's. Over half of the donors were seen to have the APOE gene, a strong genetic risk factor for Alzheimer's disease. Researchers, however, found a stronger association between traffic-related air pollution and signs of Alzheimer's disease in donors not already genetically predisposed.

The Atlanta skyline. A new study from Emory University researchers using tissue donated by metro Atlanta residents found association between traffic-related air pollution and Alzheimer’s disease in humans. The study does not prove air pollution causes Alzheimer’s, but it found an association between exposure to air pollution caused by traffic and signs of Alzheimer’s in brain tissue. [ JOHN SPINK | TNS ]

"We often think about air pollution in the lungs, but it's critical that we put the brain at the forefront of the conversation of the ways that air pollution impacts our health."

Gaurab Basu, director of Education and policy, Harvard centre for climate, health and the environment