Can Air Pollution Contribute to Dementia, Too?

By Susanne Rust, California Watch

It’s well established that dirty, sooty air is no good for your lungs and probably not great for your skin. But new research indicates it can damage your brain, too.

A study in the journal of the Archives of Internal Medicine shows that air pollution accelerates cognitive decline in women.

And with a new federal report showing Southern Californians are at the highest risk of death due to air pollution, this study adds to the growing body of grim evidence showing air pollution and healthy bodies don’t mix.

“We keep learning about more adverse effects (from pollution) than we thought possible,” said Jean Ospital, health effects officer with the South Coast Air Quality Management District, who was not involved with the current research.

“I’m not sure I find these results surprising,” he said, “but I’m also not sure I would have expected them if you’d asked me 10 years ago.”

The new research, conducted by a team of researchers from Chicago, Boston, Baltimore and Philadelphia, looked at the effect of coarse particulate matter in the air on the cognitive health of older women.

“We, as a society, are on the verge of dealing with an unprecedented number of people having dementia,” said Jennifer Weuve, lead author of the study and a researcher at Chicago’s Rush University Medical Center. “We know relatively little about how to prevent dementia, but we do know cognitive decline is related to dementia.”

Weuve pointed to research showing a link between air pollution and cardiovascular disease.

“It turns out that cardiovascular disease may play a role in cognitive decline," said Weuve, who is a researcher at Rush’s Institute for Healthy Aging. "So if we understand how to prevent or delay these cognitive increments, maybe we can prevent or delay dementia.”

And not just at an individual level, she said.

“What’s interesting about air pollution," Weuve said, is that “other factors that may cause dementia are generally found at the more individual level – diet, weight, smoking. And we can help to try to prevent them at that level. But in this case, we’re looking at something that we can do to intervene at a broad scale, with society at large."

"It's a whole new way to think about prevention for dementia and cognitive decline," she said.

Weuve and her team turned to one of the largest epidemiological datasets and cohorts in medical research, the Nurses' Health Study, to begin looking for links between pollution and cognitive health.

The Nurses' Health Study, which researchers began in 1976, is a dataset based on information collected over time from 121,700 female registered nurses between the ages of 30 and 55 living in 11 different states.

Between 1995 and 2001, Weuve and her colleagues invited participants of the Nurses' Health Study to participate in a study of cognition. The team was able to get data from nearly 20,000 women.

To establish pollutant exposure, the team collected air pollution exposure data from the Environmental Protection Agency, which they correlated with the location of each woman's home and place of employment. Then they called each woman six times on the phone, over six years, and tested their cognitive abilities.

They found that higher levels of long-term exposure to air pollution particles was associated with significantly faster cognitive decline.

She said more research needs to be done. For instance, is the cognitive decline they observed due to cardiovascular issues, or are pollutants having a direct effect on the brain?

She said more research also will be needed to confirm her work.

"The bottom line," said Sam Atwood, a spokesman for the South Coast Air Quality Management District, "is that in Southern California, we have some of the highest levels of particulate matter in the country, and we are working as quickly as possible at reducing those levels."