UC Irvine

Exposure to elevated levels of ambient air pollution particulate matter (PM), is associated with cognitive decline. In this study we examined the impacts of different sizes of PM (concentrated coarse (Dp ≤ 10 µm), concentrated fine (Dp ≤ 2.5 µm), and ultrafine PM (Dp ≤ 200 nm)) on memory in mice using two standard behavioral tests; the object location test (OLM) and the novel object recognition test (ORM). Secondary variables that were examined via behavioral testing included: sex (M vs. F), diet (high fat vs. normal chow diet), and mouse genotype. We used C57BL/6 mice from 2 studies, CEDARS (3xTg-AD mice) which were genetically modified to develop Alzheimer’s Disease, and RESTORE (ApoE KO mice and Ldlr KO mice) which can be hyperlipedemic and develop arterial plaques. These models were chosen to examine the potential impacts of ambient PM on neurodegenerative changes in exposed normal and compromised mice. Both studies were examined individually with respect to impact of PM exposure on behavioral test outcomes and were then compared with respect to the secondary independent variables, genetic modification and sex. There were no statistically significant changes in the Cedars study as a function of PM size. There were, however, statistically significant changes in OLM and ORM memory tasks based on exposure length, sex, genetic predisposition, and diet. The data suggests that these factors can interact with environmental PM exposure to impact memory performance. This analysis did have some limitations including; multiple people analyzed the behavior data, which could have increased variability in the results and there were losses of animals in some groups due to attrition, which reduced the power of the statistical analyses.