In Polluted Cities, Kids Show Hallmarks of Alzheimer's Disease

Alzheimer’s disease may get a very early start in people living in polluted megacities, according to a new study published in the Journal of Environmental Research. The University of Montana (UM) researchers detected early stages of the disease in babies less than a year old.

The researchers believe that the harmful effects begin when tiny pollution particles enter the brain through the nose, lungs and gastrointestinal tract; these particles then proceed to damage all barriers and travel throughout the body via the circulatory system.

For the study, the research team studied 203 autopsies of Mexico City residents between the ages of 11 months and 40 years. Mexico City is home to 24 million people exposed daily to concentrations of fine particulate matter and ozone above U.S. Environmental Protection Agency standards.

The researchers focused on two abnormal proteins that indicate development of Alzheimer’s, hyperphosphorylated tau and beta amyloid. They detected the early stages of the disease in babies less than a year old.

“Alzheimer’s disease hallmarks start in childhood in polluted environments, and we must implement effective preventative measures early,” said Dr. Lilian Calderón-Garcidueñas, a physician and Ph.D. toxicologist in UM’s Department of Biomedical and Pharmaceutical Sciences. “It is useless to take reactive actions decades later.”

The autopsy findings reveal greater levels of both hyperphosphorylated tau and beta amyloid in the brains of urban youth with lifetime exposure to fine-particulate-matter pollution, or PM2.5. These particles are at least 30 times smaller than the diameter of a human hair and frequently cause the haze over urban areas.

The researchers also tracked Apolipoprotein E (APOE 4), a well-known genetic risk factor for Alzheimer’s, as well as lifetime cumulative exposure to unhealthy levels of PM2.5.

Hallmarks of the disease were found among 99.5 percent of the Mexico City subjects. The findings suggest that Alzheimer’s begins in early childhood, and that disease progression relates to age, APOE 4 status and particulate exposure.

In addition, APOE 4 carriers have a higher risk of rapid progression of Alzheimer’s and 4.92 higher odds of committing suicide versus APOE 3 carriers, controlling for age and particulate exposure.

Overall, the researchers discovered an accelerated and early disease process for Alzheimer’s in highly exposed Mexico City residents. They believe the harmful effects are due to tiny pollution particles that enter the brain through the nose, lungs and gastrointestinal tract; these particles damage all barriers and travel everywhere in the body through the circulatory system.

The researchers conclude that air pollution is a key modifiable risk for millions of people around the world, including millions of Americans who are exposed to harmful particulate pollution levels.

“Neuroprotection measures ought to start very early, including the prenatal period and childhood,” said Calderón-Garcidueñas. “Defining pediatric environmental, nutritional, metabolic and genetic risk-factor interactions are key to preventing Alzheimer’s disease.”

Source: University of Montana