Kwokyan William Tsoi

Project title: A Prospective Cohort Study to Estimate the Effect of Ultrafine Particulate Matter (UFP) Air Pollution on Alzheimer's Disease Neuropathology at Autopsy in Puget Sound

Degree: MPH | Program: Occupational and Environmental Medicine (OEM) | Project type: Thesis/Dissertation
Completed in: 2023 | Faculty advisor: Lianne Sheppard


Background: Evidence links air pollution to Alzheimer’s disease (AD). The health effect of ultrafine particulate matter (UFP) air pollution is not well understood, and no community-based prospective cohort studies in older adults have evaluated the association between UFP and markers of AD neuropathology at autopsy. Objective: Using a well-established autopsy cohort and Adult Change in Thought (ACT) mobile monitoring model, we evaluated the associations of 10-year annual average UFP exposure prior to death with Braak staging and Consortium to Establish a Registry for AD (CERAD) scores. Methods: We used autopsy specimens (N=608) from the ACT study, with enrollment ongoing since 2005. We assigned annual average UFP exposure at residential address based on ACT UFP exposure spatial model. Adjusting covariates for confounders and precision variables, we performed logistic regression on dichotomized Braak staging and CERAD scores. Results: 10-year annual average UFP exposure from death was 10292 particles per cm3 (pt/cm3), while interquartile range (IQR) was 1913 pt/cm3. For every 10-year annual average UFP IQR increase from death, the odds of having a clinically significant Braak staging ranges between 0.80 and 1.11; and the odds of having a clinically significant CERAD score ranges between 0.82 and 1.13. Our results can be interpreted to have a wide range of effects, including no effects by UFP exposure on AD neuropathology. Sensitivity Case Study: Aircrafts are high level UFP producers. We developed research methodology to create AERMOD SEATAC aircraft traffic UFP emissions spatial model. In the future, this model can be applied independently or enhance ACT spatial model resolution.