Air pollution could worsen Alzheimer’s and dementia symptoms, according to a new study.
Researchers at the Perelman School of Medicine at the University of Pennsylvania have found that air pollution may accelerate the buildup of toxic proteins in the brain, which can speed up cognitive decline.
The study, published in JAMA Neurology, investigated how fine particle matter (PM2.5) was linked to brain changes seen in dementia and Alzheimer’s and the severity of symptoms.
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The brains of 602 people were examined after death at the Penn Medicine Brain Bank from 1999 to 2022. This data was analyzed from January to June 2025.
The participants included those with common dementias and movement disorders, as well as older adults without dementia.
The study suggests that pollution may contribute to dementia by actively driving changes in the brain. (iStock)
The researchers estimated how much air pollution each person was exposed to in the year before death or prior to their last dementia assessment, based on their home address.
People exposed to higher pollution were found to have more advanced Alzheimer’s-type changes in their brains.
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Each increase in PM2.5 was linked to 19% higher odds of having more severe Alzheimer’s.
Those who lived in areas with high concentrations of PM2.5 with advanced pathology had greater cognitive impairment and more rapid onset of symptoms like memory loss, difficulty with speech and poor judgment. (iStock)
The study also considered a smaller group of 287 people who had dementia assessments before death.
For this group, higher PM2.5 exposure was linked to worsened cognitive and functional decline, including memory loss, impaired judgment, and difficulty with personal care and speech.
About 63% of the link between air pollution and dementia severity could be explained by Alzheimer’s-related brain changes, according to the researchers.
Edward Lee, M.D., Ph.D., co-director of Penn’s Institute on Aging, commented on these findings in a press release for the study.
"This study shows that air pollution doesn’t just increase the risk of dementia — it actually makes Alzheimer’s disease worse," he said. "As researchers continue to search for new treatments, it’s important to uncover all the factors that contribute to the disease, including the influence of the environment in which they live."
Lee added that air pollution in the U.S. is at the "lowest levels in decades," but even just a year living in a high-pollutant area can have a "big impact on a person’s risk of developing Alzheimer’s disease."
About 63% of the link between air pollution and dementia severity could be explained by Alzheimer’s-related brain changes, according to the researchers. (iStock)
The study did have some limitations, the researchers acknowledged.
The individuals studied were primarily White, highly educated and from "advantaged neighborhoods." The study also focused on Alzheimer's and was not representative of other forms of dementia.
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The study also could have underestimated air pollution's impact on blood vessels in the brain, they noted.
This research was funded by the National Institutes of Health and the National Institute of Environmental Health Sciences.