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 Res Rev

Institution: Ageing Res Rev

DOI: 10.1016/j.arr.2021.101504

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

Abstract

Overview

Dementia, a complex neurodegenerative disease, is influenced by various natural, physical, and social environmental factors. This systematic review collates significant data to understand these associations.

Methods

  • Extensive database search up to January 11, 2021, across PubMed, EMBASE, Web of Science, and PsychINFO.
  • Assessment of 48,399 publications, pinning down 185 relevant studies covering 44 environmental factors. Use of hazard ratio (HR), relative risk (RR), and odds ratio (OR) with 95% confidence interval (CI) evaluated using random-effects methods.
  • Evaluation of literature quality from high-to-moderate and low-to-very low.

Findings

  • Strong associations found for PM2.5 and NO2 with risks for dementia indicated by HRs.
  • Exposure to electromagnetic fields, despite lower quality of evidence, positively associated with dementia, more specifically with Alzheimer’s disease (AD).
  • Protective effects observed with increased social contact and residential greenness.
  • Other risk factors included aluminum, solvents, and proximity to roads.
  • No significant links found with noise, silicon, and several community factors.

Conclusion

The study underscores the critical impact of certain environmental factors like air pollution and highlights potential risks associated with electromagnetic fields on cognitive health and dementia.

dementia cognitive impairment environmental factors electromagnetic fields systematic review
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