In a new study, researchers found that among older Americans with cognitive impairment, the greater the air pollution in their neighborhood, the higher the likelihood of amyloid plaques—a hallmark of Alzheimer’s disease.
The study adds to evidence that pollution from cars, factories, power plants, and forest fires joins dementia risk factors like smoking and diabetes.
The research was conducted by a team at UC San Francisco and elsewhere.
In the study, the researchers looked at the PET scans of more than 18,000 seniors whose average age was 75.
The participants had dementia or mild cognitive impairment and lived in zip codes dotted throughout the nation.
The researchers found that those in the most polluted areas had a 10% increased probability of a PET scan showing amyloid plaques, compared to those in the least polluted areas.
When applied to the U.S. population, with an estimated 5.8 million people over 65 with Alzheimer’s disease, high exposure to microscopic airborne particles may be implicated in tens of thousands of cases.
This study provides additional evidence that air pollution is a big risk factor for Alzheimer’s disease and dementia.
The team says exposure in our daily lives to PM2.5, even at levels that would be considered normal, could contribute to induce a chronic inflammatory response.
Over time, this could impact brain health in a number of ways, including contributing to an accumulation of amyloid plaques.
The study complements previous large-scale studies that tie air pollution to dementia and Parkinson’s disease and adds novel findings by including a cohort with mild cognitive impairment—a frequent precursor to dementia—and using amyloid plaques as a biomarker of disease.
One author of the study is Gil Rabinovici, MD, at the UCSF Memory and Aging Center.
The study is published in JAMA Neurology.
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