By Susan Bird – CARE2: Air Pollution May Be Causing 20 Percent of Alzheimer’s and Dementia Cases

It seems that air pollution isn’t simply a threat to your lungs – it’s a threat to your cognitive function as well. If you’re an older woman and you live in an area with significant air pollution, you have a high risk of developing Alzheimer’s disease or other forms of dementia.

In fact, your risk is 90 percent higher, says a new study by the Leonard Davis School of Gerontology at the University of Southern California (USC). Women who carry the genetic variant APOE-e4 have it even worse. They are three times more likely to develop some form of dementia than women who are not APOE-e4 carriers.

The study spent 10 years looking at 3,647 women from 48 states who ranged in age from 65 and 79. None of them had any sort of dementia when the study began. Researchers gauged each woman’s cognitive function annually. They also investigated each woman’s daily exposure to PM2.5, a type of fine particle that is an air pollutant emitted from combustion sources like vehicles and power plants.

What is PM2.5?

PM2.5 is particulate matter that’s perhaps 30 times smaller than a human hair. That means, of course, we can inhale them easily – and we all do. You’re doing it every time you breathe in fumes from anything that’s burning, whether it’s a car’s exhaust, a wood fire, smog or smoke from a factory chimney. Particulates you inhale can go deep into your lungs and your bloodstream.

The Environmental Protection Agency (EPA) regulates particulate matter as one of six principal criteria pollutants via its National Ambient Air Quality Standards. Particulate matter can be responsible for health problems like asthma, lung disease and cardiovascular disease.

Breathing Too Much PM2.5 Tied to “Global Cognitive Decline”

Women who lived in areas exceeding the EPA permissible limit for PM2.5 generally fared much worse over the years than women who lived in clean air areas. Many experienced “global cognitive decline,” which is a loss of memory and reasoning skills that isn’t quite dementia, but is pretty close. The study determined that women living in these more polluted areas had an 81 percent greater risk of suffering global cognitive decline.

These results held true even after adjusting for possible bias associated with geographic region, race, ethnic background, education, socioeconomic status, lifestyle and medical conditions. This study only reinforces conclusions reached by prior studies – air pollution affects how your brain functions.

“Microscopic particles generated by fossil fuels get into our body directly through the nose into the brain,” Prof. Caleb Finch, study senior co-author, said in a press release. “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.”

The findings here aren’t the first time researchers have made this connection. In the early 2000s, for example, neuroscientist Lilian Calderón-Garcidueñas figured out why so many aging dogs in polluted areas of Mexico City were going a little crazy. They were confused, disoriented and sometimes failed to recognize their own human companions.

Calderón-Garcidueñas studied those dogs’ brains when they died. She determined that the brains had elevated levels of the same type of plaque that we find in the brains of Alzheimer’s sufferers.
If the USC study’s findings translate to the general population, say the researchers, it means air pollution might account for about 20 percent of all dementia cases. That’s a disturbing claim, and one worth paying attention to.
EPA tightened up particulate matter standards in 2012. That’s probably helping this problem, a bit.
“If people in the current administration are trying to reduce the cost of treating diseases, including dementia, then they should know that relaxing the Clean Air Act regulations will do the opposite,” Jiu-Chiuan Chen, study co-senior author, told the Los Angeles Times.
Indeed. Washington, are you listening? The slash and burn approach to eliminating “over-regulation” of businesses may seem desirable to the current administration right about now, but its future cost to human and animal health isn’t difficult to foresee.
One need only think back to the environmental horrors of the 1960s and 70s like Love Canal or the historic smog event that engulfed New York City in 1966. Those were bad, crazy times. We stopped those kinds of crises from happening again by enacting and then strengthening environmental laws like the Clean Air Act, the Clean Water Act and more.
Now all that environmental progress may change. Have our politicians been inhaling too much PM 2.5, perhaps? Can we convince our lawmakers to show restraint when changing our environmental laws? That remains to be seen, but we absolutely have to try.
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