Subgroup analysis for residential greenness and cognitive function
| Covariates | Serial cross-sectional analysis (n=38 327) | Longitudinal analysis (n=19 726) | ||
| Linear regression | Logistic regression | Linear mixed effects regression | Mixed effects logistic regression | |
| Coefficient for change of MMSE score (95% CI) | OR of cognitive impairment (95% CI) | Coefficient for change of MMSE score (95% CI) | OR of cognitive impairment (95% CI) | |
| Stratified by gender | ||||
| Males (n=15 747) | 0.20 (0.11 to 0.30) | 0.93 (0.90 to 0.96) | 0.083 (−0.0042 to 0.17) | 0.98 (0.95 to 1.02) |
| Females (n=22 580) | 0.24 (0.15 to 0.33) | 0.94 (0.92 to 0.97) | 0.060 (−0.032 to 0.15) | 0.99 (0.96 to 1.02) |
| P value for interaction | 0.31 | 0.003 | 0.051 | 0.044 |
| Stratified by residence | ||||
| Urban area (n=9076) | 0.36 (0.24 to 0.49) | 0.92 (0.89 to 0.96) | 0.050 (−0.025 to 0.12) | 0.99 (0.94 to 1.04) |
| Rural area (n=29 251) | 0.16 (0.081 to 0.24) | 0.95 (0.93 to 0.97) | 0.11 (−0.023 to 0.24) | 0.99 (0.96 to 1.02) |
| P value for interaction | 0.007 | 0.168 | 0.333 | 0.902 |
| Stratified by physical activity | ||||
| Exercise (n=10 923) | 0.084 (−0.013 to 0.18) | 0.97 (0.94 to 1.01) | 0.027 (−0.069 to 0.12) | 1.02 (0.98 to 1.06) |
| Do not exercise (n=27 404) | 0.24 (0.16 to 0.33) | 0.93 (0.90 to 0.95) | 0.069 (−0.015 to 0.15) | 0.97 (0.95 to 1.00) |
| P value for interaction | 0.025 | <0.001 | 0.136 | 0.009 |
All the regression models on 0.1-unit NDVI and cognitive function were adjusted for age, gender, ethnicity, marital status, urban/rural residence, education, occupation, financial support, social and leisure activity, smoking status, alcohol consumption and physical activity at baseline. The longitudinal analysis was additionally adjusted for the time to reflect the number of years for each follow-up survey since entering the cohort.
MMSE, Mini-Mental State Examination; NDVI, Normalised Difference Vegetation Index.