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Meta-Analysis
. 2022 Dec;9(4):574-590.
doi: 10.1007/s40572-022-00365-5. Epub 2022 Jul 20.

Is Greenness Associated with Dementia? A Systematic Review and Dose-Response Meta-analysis

Federico Zagnoli  1 , Tommaso Filippini  1   2 , Marcia P Jimenez  3 , Lauren A Wise  3 , Elizabeth E Hatch  3 , Marco Vinceti  4   5
Affiliations
Meta-Analysis

Is Greenness Associated with Dementia? A Systematic Review and Dose-Response Meta-analysis

Federico Zagnoli et al. Curr Environ Health Rep. 2022 Dec.

Abstract

Purpose of review: We assessed the relation between environmental greenness and risk of dementia and cognitive impairment, based on a systematic review and meta-analysis up to March 30, 2022, characterizing whenever possible the shape of the association using dose-response meta-analysis.

Recent findings: Twelve studies were included in this review, either using normalized difference vegetation index (NDVI) or land use/cover (LU/LC) methodology to assess greenness. Comparing the highest versus lowest exposure categories of greenness assessed using the NDVI (6 studies) or LU/LC (6 studies), we found no association with dementia. Dose-response meta-analysis of the association between greenness measured by LU/LC and dementia, based on only 3 studies, indicated a U-shaped association, but estimates were imprecise. Our systematic review and meta-analysis provided some evidence of a slight inverse association between greenness and dementia at intermediate exposure levels, but not at high levels. Potential methodological limitations, such as exposure misclassification and unmeasured confounding, may have affected the results.

Keywords: Cognitive impairment; Dementia; Green space; Greenness; Land use; NDVI.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Flow diagram of study selection process
Fig. 2
Fig. 2
Risk ratio (RR) with 95% confidence interval (CI) between exposure to greenness measured by normalized difference vegetation index (NDVI) or land use/land cover (LU/LC) and dementia. The squares represent risk estimate, and horizontal lines represent their 95% CI. The area of each square is proportional with the weight of the study in the meta-analysis. The diamonds represent the combined risk for each type of exposure, and the solid line represents null value. The inverse-variance estimation method was used for study weighting. AD, Alzheimer’s disease; NAD, non-Alzheimer’s dementia
Fig. 3
Fig. 3
Dose–response of dementia and greenness measured by land use/land cover (LU/LC). Spline curve (black solid line) with 95% confidence limits (black dashed lines). RR, relative risk
Fig. 4
Fig. 4
Risk ratio (RR) with 95% confidence interval (CI) between exposure to greenness measured by normalized difference vegetation index (NDVI) or land use/land cover (LU/LC) and cognitive impairment. The squares represent risk estimate, and horizontal lines represent their 95% CI. The area of each square is proportional with the weight of the study in the meta-analysis. The diamonds represent the combined risk for each type of exposure, and the solid line represents null value. The inverse–variance estimation method was used for study weighting
See this image and copyright information in PMC

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