Poorer air quality correlates with development of amyloid-beta plaques
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Greater amounts of air particulate matter correlated with the development of brain amyloid-beta plaques among older adults with cognitive impairment from over 5,000 U.S. Census tracts, according to a secondary analysis of the IDEAS study.
Researchers published the findings from the IDEAS: Imaging Dementia — Evidence for Amyloid Scanning study in JAMA Neurology.
“We leveraged the large, geographically distributed IDEAS Study cohort to examine the associations between the likelihood of amyloid PET scan positivity and ambient air quality, as measured in data provided by the Downscaler model (which combines pollutant concentrations, photochemical properties, and atmospheric data) of the US Environmental Protection Agency (EPA),” Leonardo Iaccarino, PhD, a postdoctoral fellow in imaging at University of California, San Francisco, and colleagues wrote. “We hypothesized that IDEAS Study participants who lived in areas with higher concentrations of airborne pollutants would be more likely to have positive amyloid PET scan results.”
Iaccarino and colleagues conducted a secondary cross-sectional analysis of data from the IDEAS study, in which participants with cognitive impairment received an amyloid PET scan. Iaccarino and colleagues examined data from 18,178 IDEAS participants (mean age, 75.8 years; women, 51.3%) whose demographic, amyloid PET scan status and residential zip code data were available. They used data from the Environmental Protection Agency’s Downscaler model to evaluate air pollution, a model that merges air quality monitoring and atmospheric modeling. Researchers evaluated environmental data from 2002 to 2003 and from 2015 to 2016.
All participants had some form of cognitive impairment, including 10,991 (60.5%) with mild cognitive impairment and 7,817 (39.5%) with dementia.
Living in an area with greater concentrations of fine particulate matter correlated with increased odds for amyloid PET scan positivity from2002 to 2003 (adjusted OR [aOR] = 1.10; 95% CI, 1.05-1.15) as well as from 2015 to 2016 (OR = 1.15; 95% CI, 1.05-1.26). Participants living in the quartile with the most pollution had greater odds for having a positive PET scan from 2002 to 2003 (OR = 1.27; 95% CI, 1.16-1.4) as well as from 2015 to 2016 (OR = 1.14; 95% CI, 1.04-1.25). Fine particulate matter concentrations overall improved from the first time window (2002-2003) to the second (2015-2016) by a mean of -4.11 g/m3.
Post hoc analyses demonstrated no effect modification of sex or clinical stage (mild cognitive impairment or dementia). In addition, the researchers found no association between ground-level ozone and positive amyloid PET scan.
“In this cross-sectional study, we observed an association between air pollution and [amyloid beta] pathology in older adults with cognitive impairment who were enrolled in the IDEAS Study, a finding with strong biological plausibility based on bench-to-bedside evidence,” the researchers wrote. “Adverse effects of airborne toxic pollutants associated with [amyloid beta] pathology should be considered in public health policy decisions and should inform individual lifetime risk of developing [Alzheimer’s disease] and dementia.”
Editor’s note: The Alzheimer’s Association also announced the start of recruitment for the New IDEAS Study, which aims to determine if amyloid PET scans improve diagnosis and treatment of Alzheimer’s disease. To learn more, click here .