New research out of the University of Montana adds to the building evidence that dementia, Alzheimer’s and suicide rates are linked to air pollution—in particular the small particulates found in polluted city air.
Dr. Lilian Calderón-Garcidueñas said her group studied 203 autopsies of Mexico City residents ranging in age from 11 months to 40 years. Metropolitan 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 tracked two abnormal proteins that indicate development of Alzheimer's, and 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 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."
As Dr. Calderón-Garcidueñas and her team write, these are “modifiable” factors. If we work to lessen the amount of pollution in our air, the less this will be a problem for us or our children, or our children’s children. It’s not even math, it’s common sense.
Findings indicate Alzheimer's starts in early childhood, and the disease progression relates to age, APOE 4 status and particulate exposure. Researchers found hallmarks of the disease among 99.5 percent of the subjects they examined in Mexico City. 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.
There has been research connecting air pollution with its effects on the brains of animals but comprehensive research on what that means for humans has been tougher to accomplish.
That’s not easy to do, as long-term, historical data on pollution exposures are scarce in the United States and many other countries, says Kimberly Gray, a program administrator at the National Institute of Environmental Health Sciences (NIEHS) in Durham, North Carolina. But in a September 2016 review of 18 epidemiological studies from Taiwan, Sweden, Germany, China, the United Kingdom, and the United States, all but one showed an association between high exposure to at least one component of air pollution and a sign of dementia. The review, published in Neurotoxicology, included a 2012 analysis of 19,000 retired U.S. nurses, which found that the more fine particulates the nurses were exposed to, based on monitoring data near their homes, the faster they declined on cognitive tests. For every additional 10 micrograms per cubic meter of air they breathed, their performance on tests of memory and attention declined as if they had aged by 2 years, says Jennifer Weuve, an epidemiologist at Boston University, who led the analysis.
Imaging studies also suggest that pollution attacks the human brain. In a 2015 analysis of brain MRI scans of people enrolled in the Framingham Heart Study, a long-term cardiovascular study in New England, researchers at Harvard Medical School in Boston found that the closer people had lived to a major roadway—and thus the more PM2.5 they had likely been exposed to—the smaller their cerebral brain volume. The association held up even after adjusting for factors such as education, smoking, diabetes, and cardiovascular disease.
We all know that pollution in the air, in our water, or in our food supply cannot be “good” for us. The more and more scientific research done does not disabuse us of this notion—it only shows us how much worse it is.