The role of the components of PM in the incidence of Alzheimer's disease and related disorders.

BACKGROUND

The associations of PM mass and various adverse health outcomes have been widely investigated. However, fewer studies focused on the potential health impacts of PM components, especially for dementia and Alzheimer's diseases (AD).

METHODS

We constructed a nationwide population-based open cohort study among Medicare beneficiaries aged 65 or older during 2000-2018. This dataset was linked with the predicted levels of 15 PM components, including 5 major mass contributors (EC, OC, NH, NO, SO) and 10 trace elements (Br, Ca, Cu, Fe, K, Ni, Pb, Si, V, Zn) across contiguous U.S. territory. Data were aggregated by ZIP code, calendar year and individual level demographics. Two mixture analysis methods, weighted quantile sum regression (WQS) and quantile g-computation (qgcomp), were used with quasi-Poisson models to analyze the health effects of the total mixture of PM components on dementia and AD, as well as the relative contribution of individual components.

RESULTS

Exposure to PM components over the previous 5 years was significantly associated with increased risks of both dementia and AD, with stronger associations observed for AD. SO, OC, Cu were identified as major contributors to the combined positive association of the mixture from both WQS and qgcomp models.

CONCLUSION

We found positive associations between the 15 PM components and the incidence of dementia and AD. Our findings suggest that reducing PM emissions from traffic and fossil fuel combustion could help mitigate the growing burden of dementia and Alzheimer's disease.