Yilin Tang, Zhenyu Li, Yicheng Fu, Mingyi Zhao This email address is being protected from spambots. You need JavaScript enabled to view it. 

Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, Hunan 410013, China

Received: January 26, 2024
Revised: May 13, 2024
Accepted: May 31, 2024

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.230326  

Cite this article:

Tang, Y., Li, Z., Fu, Y., Zhao, M. (2024). Causal Effects of PM2.5, NOx, and NO2 on Cognitive Function: A Two-sample Mendelian Randomization Study. Aerosol Air Qual. Res. 24, 230326. https://doi.org/10.4209/aaqr.230326


  • This is the first MR analysis of air pollution and cognition impairment.
  • NOx can reduce cognitive function.
  • There is no causal relationship between PM2.5, NO2, and cognitive function.


Epidemiological studies have revealed that air pollutants are related to cognitive decline, but a causal relationship has not been established. We conducted a two-sample Mendelian randomization (MR) study using pooled statistics from publicly available genome-wide association study (GWAS) data to show the association between air pollutants and cognitive decline in the European population. The exposure factors in our analysis were air pollutants, including “particulate matter air pollution (PM2.5); 2010”, “nitrogen oxides air pollution; 2010” and “nitrogen dioxide air pollution; 2010”, while our outcome variables focused on cognitive function, including the “fluid intelligence score”, “mean time to correctly identify matches”, and “number of incorrect matches in the round”. We applied various MR methods, including inverse-variance weighted (IVW), weighted median, and MR-Egger regression, to estimate the causal effects. Furthermore, we conducted heterogeneity and pleiotropy tests to ensure the robustness of our findings. Our study revealed a significant negative correlation between NOx and fluid intelligence scores (β-0.879, 95% CI [–1.423, –0.336], p = 0.002), indicating that among air pollutants, NOx has a detrimental impact on cognitive function. No significant associations were found between PM2.5 or NO2 and cognitive function. The presence of NOx is associated with a decrease in the fluid intelligence score, suggesting adverse effects of NOx on logic and reasoning skills. These findings further emphasize the importance of preventing and treating air pollution exposure and suggest that early cognitive screening in people exposed to air pollution can prevent the development of neurodegenerative diseases.

Keywords: PM2.5, NO2, NOx, Cognitive function

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