Comparing traditional and causal inference methodologies for evaluating impacts of long-term air pollution exposure on hospitalization with Alzheimer disease and related dementias

Abstract

Alzheimer disease and related dementias (ADRDs) present a growing public health burden in the United States. One actionable risk factor for ADRDs is air pollution: multiple studies have found associations between air pollution and exacerbation of ADRDs. Our study builds on previous studies by applying modern statistical causal inference methodologies—generalized propensity score (GPS) weighting and matching—on a large, longitudinal data set.

We follow 50 million Medicare enrollees to investigate impacts of 3 air pollutants—fine particular matter (PM2.5), nitrogen dioxide (NO2), and summer ozone (O3)—on elderly patients’ rate of first hospitalization with an ADRD diagnosis. Similar to previous studies using traditional statistical models, our results found increased hospitalization risks due to increased PM2.5 and NO2 exposure, with less conclusive results for O3. In particular, our GPS weighting approach provides robust evidence for the causal relationship between air pollution exposure and ADRD hospitalizations.

Key Contributions

• Large-Scale Analysis: Analysis of 50 million Medicare enrollees in a comprehensive longitudinal study
• Causal Inference Methods: Application of modern causal inference techniques including generalized propensity score weighting and matching
• Multi-Pollutant Assessment: Evaluation of three key air pollutants (PM2.5, NO2, and O3) and their differential impacts
• Methodological Comparison: Direct comparison of traditional statistical models with causal inference approaches
• Public Health Impact: Provides evidence for actionable interventions to reduce ADRD burden through air quality improvements

Clinical and Policy Implications

This research contributes to the growing body of evidence linking air pollution to cognitive decline and dementia, with important implications for environmental health policy and clinical practice. The findings support the need for stricter air quality standards and targeted interventions to protect vulnerable elderly populations from the adverse effects of air pollution on neurological health.

Recommended citation: Qin, M. M., Khoshnevis, N., Dominici, F., Braun, D., Zanobetti, A., & Mork, D. (2025). Comparing traditional and causal inference methodologies for evaluating impacts of long-term air pollution exposure on hospitalization with Alzheimer disease and related dementias. American Journal of Epidemiology, 194(1), 64-72. https://doi.org/10.1093/aje/kwae427
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