Environmental factors and risks of cognitive impairment and dementia: A systematic review and meta-analysis

Authors: Yong-Li Zhao, Yi Qu, Ya-Nan Ou, Ya-Ru Zhang, Lan Tan, Jin-Tai Yu

Year: 2021 Oct 29

Category: Epidemiology

Journal: Ageing Research Reviews

DOI: 10.1016/j.arr.2021.101504

URL: https://pubmed.ncbi.nlm.nih.gov/34755643/

Abstract

Overview

Dementia is a challenging neurodegenerative disease. This systematic review aimed to summarize natural, physical, and social environmental factors that are associated with age-related cognitive impairment and dementia.

Methods

  • Systematic searches were conducted across multiple databases including PubMed, EMBASE, Web of Science, and PsychINFO until January 11, 2021.
  • Observational studies were reviewed, aggregating hazard ratio (HR), relative risk (RR), and odds ratio (OR) using random-effects methods.
  • The quality of evidence for each association was evaluated to ensure robustness of the findings.

Findings

A total of 48,399 publications were identified, with 185 found suitable for review. Meta-analyses for 22 environmental factors showed:

  • Significant risks associated with particulate matter (PM2.5 and NO2) and proximity to roads.
  • Exposure to electromagnetic fields was found positively associated with dementia, suggesting a potential health risk.
  • Benefits were noted with increased social contacts and residential greenness.

Conclusion

This review highlights the critical impact of air pollution, particularly PM2.5 and NO2, on the risk for age-related cognitive impairment and dementia. The associations between electromagnetic fields and dementia require careful consideration due to potential health risks, even though the quality of evidence is low to very low.

dementia cognitive impairment electromagnetic fields environmental factors meta-analysis
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