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Polluted Air Tied to Memory Problems, Even in the Short Term

May 17, 2021

Living for years in areas high in smog and other air pollutants may contribute to memory loss and increase the risk of developing Alzheimer’s disease, a growing body of evidence shows. A new study found that even over the course of a few weeks, breathing in air pollutants may lead to declines in memory and thinking skills. But taking aspirin and similar nonsteroidal anti-inflammatory drugs may help to counter the cognitive deficits caused by air pollution, the study found.

For the study, researchers at Columbia University’s Mailman School of Public Health looked at 954 men in their 60s and 70s who were living in the Boston metropolitan area. All were part of an ongoing study of veterans.

The men took tests of memory and thinking skills at the start of the study, and over the next 28 days. The researchers also recorded air levels of soot and other tiny pollutant particles that can be breathed in through the lungs, where they move into the bloodstream and can enter the brain.

The researchers found that on days with high pollutant levels, the men scored worse on tests of memory and thinking skills. But they also found that men who were taking aspirin or other nonsteroidal anti-inflammatory drugs seemed to show less declines in cognitive skills. The drugs are commonly taken for heart health and as pain relievers, but they seemed to help protect the brain against the short-term effects of pollutants.

“Short-term spikes in air pollution remain frequent and have the potential to impair health, including at levels below that usually considered hazardous,” said the senior author of the study, Dr. Andrea Baccarelli. “Taking aspirin or other anti-inflammatory drugs appears to mitigate these effects.” The findings were published in Nature Aging.

The researchers aren’t sure why anti-inflammatory drugs may help counter the effects of air pollution, but they speculated that it likely curbs the deleterious inflammatory effects of pollutants on the brain. Animal studies have recorded higher levels of brain inflammation in animals exposed to polluted air, and increasingly, scientists believe that inflammation may play a role in Alzheimer’s disease as well, especially chronic or prolonged inflammation. They said further research is needed to explore the connection.

The findings add to growing evidence of the harmful effects of pollution on the brain. Earlier studies have shown, for example, that women who live in areas with the worst quality air scored lower on tests of memory and thinking than those who lived in cleaner areas. Other studies have shown that living in areas with heavily polluted air, whether from car emissions, power plants, factories or forest fires, can accelerate the onset of Alzheimer’s in people who may already be vulnerable to developing the disease. People who live in polluted areas also tend to have higher levels of the telltale brain plaques tied to Alzheimer’s disease.

It is difficult to establish a direct link between environmental toxins and a disease like Alzheimer’s, because so many factors are involved, the exposure level over the years might be difficult to evaluate, and correlation does not equal causation. But air pollution has been cited as a risk factor for Alzheimer’s disease, along with such factors as hearing loss, smoking, high blood pressure, obesity, depression, lack of social contact and being sedentary.

Little can be done at present to stop the progression of Alzheimer’s disease. Drugs may ease symptoms for a time, but do not stop the underlying disease process. And researchers still do not understand what causes Alzheimer’s disease. Government efforts to tighten air pollution exposure standards in the future may help reduce the risk of Alzheimer’s disease, experts say. And further research will help to elucidate the possible benefits of taking anti-inflammatory drugs on the brain.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Xu Gao, Brent Coull, Xihong Lin, et al: “Short-term Air Pollution, Cognitive Performance and Nonsteroidal Anti-Inflammatory Drug Use in the Veterans Affairs Normative Aging Study.” Nature Aging, May 2021

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