Greenness and Parkinson’s disease prevalence: a national cross-sectional study in China

Abstract Although a few studies have explored the impact of greenness on neurodegenerative diseases, little is known about the association between greenness and Parkinson’s disease (PD) prevalence, especially in developing countries. We aimed to investigate the association between greenness and PD prevalence in China. This cross-sectional study utilized data from the 2020 wave of the China Health and Retirement Longitudinal Study (CHARLS), involving a sample of 17 029 individuals. PD diagnoses were ascertained through medical professionals and records in questionnaires. To assess greenness exposure, Normalized Difference Vegetation Index (NDVI) was calculated as annual population-weighted for 2020 (NDVI 2020 ) and a two-year average population-weighted for the period of 2019 and 2020 (NDVI 2019−2020 ), respectively. Logistic regression models were employed to analyze the association between greenness and PD prevalence at city scale, and stratified analyses were further performed to identify potential modifiers of the association between greenness and PD prevalence. In the fully-adjusted models, a 0.1 increase in NDVI 2020 was associated with 14.0% [odds ratio (OR) 0.860, 95% confidence interval (CI): 0.750, 0.987] lower odds of prevalent PD. Similarly, a 0.1 increase in NDVI 2019−2020 was associated with 13.9% (OR 0.861, 95% CI: 0.744, 0.997) reduction in the odds of prevalent PD. This conclusion remained robust in the sensitivity analyses. Moreover, significant protective effects of greenness on PD prevalence were identified among females, the elderly, those living alone, and those with healthier habits. This national cross-sectional study found that exposure to higher greenness was associated with reduced odds of prevalent PD. Greenness may serve as a readily accessible environmental intervention for lowering prevalent PD in the future.