Association between residential greenness and cognitive function: analysis of the Chinese Longitudinal Healthy Longevity Survey

Abstract

IntroductionProximity to vegetated green space has been linked to better physical and mental health. However, the relationship between residential greenness and cognitive function and its decline among older adults is not clear in large cohort studies.MethodsOur study used the 2000, 2002, 2005, 2008 and 2011 wave of the Chinese Longitudinal Healthy Longevity Survey. We calculated the Normalised Difference Vegetation Index (NDVI) using a 500 m radius around participants’ residential addresses. Mini-Mental State Examination (MMSE) was applied to measure cognitive function. Our study included the cross-sectional analysis using the linear regression, and logistical regression, and also the longitudinal analysis using the linear mixed effects regression, and mixed effects logistic regression. Our study also conducted a sensitivity analysis using the survey-weighted regression. Additionally, our study participants were categorised into those living in areas of positive and negative changes in NDVI in relation to MMSE. All regression models were adjusted for a range of covariates.ResultsAmong 38 327 participants at baseline, the mean MMSE score was 21. Annual average NDVI ranged from −0.11 to 0.76. In the cross-sectional analysis, each 0.1-unit increase in NDVI was associated with a 0.23-point increase in MMSE score (95% CI 0.16 to 0.29) in the linear regression, and an OR of 0.94 (95% CI 0.92 to 0.96) of having cognition impairment in the logistic regression. In the second analysis, looking at changes in NDVI and MMSE score, compared with the participants living in areas with an increase in NDVI, those living in areas with a decrease in greenness had an OR of 1.25 (95% CI 1.18 to 1.34) of a decrease in MMSE, and an OR of 0.90 (95% CI 0.84 to 0.96) of an increase in MMSE. In the longitudinal analysis, we found a significantly weak association (coefficient 0.069, 95% CI 0.0048 to 0.13) in the linear mixed effects regression, but not in the mixed effects logistic regression.ConclusionWe found evidence of an association between higher residential greenness and better cognitive function among older adults. Our finding provides insight into neurodegeneration and has implications for preventing dementia and Alzheimer’s disease in China.

APOE ε4 Modifies Effect of Residential Greenness on Cognitive Function among Older Adults: A Longitudinal Analysis in China

“…www.nature.com/scientificreports www.nature.com/scientificreports/ function by the clinical diagnosis 21,22 . However, it has been demonstrated that the adapted Chinese version used in our study was reliable and valid, and has been used to assess the cognitive function in a number of health studies 24,39 . Third, there might be selection bias.…”

“…Each question scored as zero (wrong or unable to answer) or one (correct). We converted the 24-item MMSE to a scale from 0 to 30 for consistency with other studies 23,24 . We categorized cognitive function into groups of having normal cognition (MMSE scores > = 24, as the reference group), and cognitive impairment (MMSE <24) 25 .…”

Green Space and Health in Mainland China: A Systematic Review

“…Serum vitamin D [ 108 ], sleep quality [ 109 ], peripheral oxygen saturation [ 36 , 83 ], cognitive function [ 110 , 111 ], markers related to immune system function such as T cell, B cell, and natural killer cell counts [ 35 , 36 , 54 ], platelet activation [ 35 ], stress marker (cortisol) and testosterone levels [ 35 , 36 , 54 ], pro-inflammatory markers such as interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-a), high-sensitivity C-reactive protein (hs-CRP), oxidative stress markers (total superoxide dismutase, malondialdehyde) ( n = 5) [ 35 , 54 , 60 , 73 , 84 ], and the presence of various chronic diseases (e.g., joint diseases, endocrine disease) [ 80 ] were other outcomes measured.…”

“…Two cohort studies that used the same dataset examined if more residential green space could protect against cognitive function [ 110 , 111 ] and impairment [ 110 ] among older adults (65+ years) ( n = 6995) at follow-up between 2 to 14 years later. Longitudinal analysis in one study did not show any association [ 110 ].…”

“…Two cohort studies that used the same dataset examined if more residential green space could protect against cognitive function [ 110 , 111 ] and impairment [ 110 ] among older adults (65+ years) ( n = 6995) at follow-up between 2 to 14 years later. Longitudinal analysis in one study did not show any association [ 110 ]. The cross-sectional analysis found that the participants living in the highest quartile of residential green space had lower odds of cognitive impairment than those in the lowest quartile.…”