New study hints at a hidden Alzheimer’s risk factor affecting older Americans

People with greater exposure to air pollution could face a higher risk of developing Alzheimer's disease, according to a new study by Emory University in Atlanta.

Air pollution has previously been established as a risk factor for Alzheimer’s, as well as other chronic conditions, like hypertension, stroke and depression, the researchers noted.

Since those other conditions are themselves linked to Alzheimer’s, the researchers said it’s not yet clear whether air pollution harms brain health on its own, or whether it raises dementia risk by first triggering those other health problems.

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The study, which was published in the journal PLOS Medicine, investigated more than 27.8 million U.S. Medicare recipients, 65 years and older, from 2000 to 2018.

The individuals were examined for level of exposure to air pollution and whether they developed Alzheimer’s, with a focus on other chronic conditions.

Greater exposure to air pollution was associated with an increased risk of Alzheimer’s, which was slightly stronger in people who had experienced a stroke. Hypertension and depression had "little additional impact," according to the study's press release.

The authors concluded that air pollution leads to Alzheimer’s mostly through "direct pathways" rather than via other chronic conditions.

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"Our findings suggest that individuals with a history of stroke may be particularly vulnerable to the harmful effects of air pollution on brain health, highlighting an important intersection between environmental and vascular risk factors," the authors wrote in a statement.

These findings suggest that improving air quality could be "an important way to prevent dementia and protect older adults," the press release concluded.

Fox News senior medical analyst Dr. Marc Siegel confirmed more studies are revealing that Alzheimer’s is linked to conditions that impact the brain, which can be "sensitive and fragile."

"Certainly, underlying medical conditions like stroke can lead to this," Siegel, who was not involved in the study, told Fox News Digital.

This latest study "does not show cause and effect," the doctor noted, but rather shows an "increasing association between air pollution and Alzheimer’s, where the particulate matter appears to increase the inflammation in the brain that helps lead to it."

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"This is another piece in developing a strategy of prevention, early diagnosis and targeted treatments," Siegel added.

Ozama Ismail, PhD, director of scientific programs at the Alzheimer’s Association in Chicago, agreed that this study adds to existing research on the impact of air pollution and overall health, especially related to the brain.

"This is an area of investigation where more research is vital to helping us better understand the connection between pollution and the various factors that cause or contribute to Alzheimer’s disease," Ismail, who also did not work on the study, told Fox News Digital.

"Previous studies, including those presented at the Alzheimer’s Association International Conference in 2019, 2021 and 2025, have shown evidence for connections between exposure to air pollution and other environmental toxins and risk for Alzheimer’s or other dementias."

The Lancet Commission on Dementia Prevention added exposure to air pollution to its list of known dementia risk factors in 2020, according to Ismail.

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"We know that Alzheimer’s is a complex disease, and it is likely that there are a variety of factors, in combination, that impact a person's lifetime risk," he said. "Avoiding exposure to air pollution is a risk factor that may be easier for some people to change than others."

Fox News Digital reached out to the study authors for comment.