Study: Air Pollution Linked to Greater Alzheimer's Risk

A recent study conducted by University of Southern California scientists found that elevated air pollution levels translated to an increased risk of cognitive decline and dementia.

The analysis, published in the Nature journal Translational Psychiatry, examined data from 3,647 women aged 65 to 79 that participated in the Women’s Health Initiative Memory Study. Participants lived in 48 states and did not have dementia at the time that they enrolled.

The study blamed PM2.5, which are tiny airborne particles largely generated by power plants and automobiles.

USC researchers said that women that lived in areas with fine particulate matter above Environmental Protection Agency standards were 81 percent more at risk for cognitive decline and 92 percent more likely to develop dementia, including Alzheimer’s.

“Cells in the brain treat these particles as invaders and react with inflammatory responses, which over the course of time, appear to exacerbate and promote Alzheimer’s disease," said co-author Caleb Finch.

Scientists said that if the same results held for the general population, about one-fifth of dementia cases could be due to air pollution.

The effects were more pronounced in women with the APOE4 gene, which increases Alzheimer's risk.

The study also showed that female mice carrying that genetic variation accumulated up to 60 percent more amyloid plaque when exposed to air pollution in a laboratory setting than a control group.

Researchers acknowledged that additional research is required to confirm air pollution's effects on the brain. They also cautioned that more accurate pollution monitoring is needed; the American Lung Association estimated that less than one-third of all counties in the U.S. have ozone or particle pollution monitors.

“We don’t know whether the lower PM2.5 levels of recent years have provided a safe margin for older Americans, especially those at risk for dementia," said co-senior author Jiu-Chiuan Chen.