Background Few studies have explored the role of air pollution in neurodegenerative processes, especially various types of dementia. Our aim was to evaluate the association between long-term exposure to air pollution and first hospitalization for dementia subtypes in a large administrative cohort. Methods We selected 350,844 subjects (free of dementia) aged 65–100 years at inclusion (21/10/2001) and followed them until 31/12/2013. We selected all subjects hospitalized for the first time with primary or secondary diagnoses of various forms of dementia. We estimated the exposure at residence using land use regression models for nitrogen oxides (NOx, NO 2 ) and particulate matter (PM) and a chemical transport model for ozone (O 3 ). We used Cox models to estimate the association between exposure and first hospitalization for dementia and its subtypes: vascular dementia (Vd), Alzheimer’s disease (Ad) and senile dementia (Sd). Results We selected 21,548 first hospitalizations for dementia (7497 for Vd, 7669 for Ad and 7833 for Sd). Overall, we observed a negative association between exposure to NO 2 (10 μg/m 3 ) and dementia hospitalizations (HR = 0.97; 95% CI: 0.96–0.99) and a positive association between exposure to O 3 , NOx and dementia hospitalizations, (O 3 : HR = 1.06; 95% CI: 1.04–1.09 per 10 μg/m 3 ; NOx: HR = 1.01; 95% CI: 1.00–1.02 per 20 μg/m 3 ).H. Exposure to NOx, NO 2 , PM 2.5 , and PM 10 was positively associated with Vd and negatively associated with Ad. Hospitalization for Sd was positively associated with exposure to O 3 (HR = 1.20; 95% CI: 1.15–1.24 per 10 μg/m 3 ). Conclusions Our results showed a positive association between exposure to NOx and O 3 and hospitalization for dementia and a negative association between NO 2 exposure and hospitalization for dementia. In the analysis by subtype, exposure to each pollutants (except O 3 ) demonstrated a positive association with vascular dementia, while O 3 exposure was associated with senile dementia. The results regarding vascular dementia are a clear indication that the brain effects of air pollution are linked with vascular damage. Electronic supplementary material The online version of this article (10.1186/s12940-019-0511-5) contains supplementary material, which is available to authorized users.
Background:Living in areas with higher levels of surrounding greenness and access to urban green areas have been associated with beneficial health outcomes. Some studies suggested a beneficial influence on mortality, but the evidence is still controversial.Objectives:We used longitudinal data from a large cohort to estimate associations of two measures of residential greenness exposure with cause-specific mortality and stroke incidence.Methods:We studied a population-based cohort of 1,263,721 residents in Rome aged ≥30y, followed from 2001 to 2013. As greenness exposure, we utilized the leaf area index (LAI), which expresses the tree canopy as the leaf area per unit ground surface area, and the normalized difference vegetation index (NDVI) within 300- and 1,000-m buffers around home addresses. We estimated the association between the two measures of residential greenness and the outcomes using Cox models, after controlling for relevant individual covariates and contextual characteristics, and explored potential mediation by air pollution [fine particulate matter with aerodynamic diameter ≤2.5μm (PM2.5) and NO2] and road traffic noise.Results:We observed 198,704 deaths from nonaccidental causes, 81,269 from cardiovascular diseases [CVDs; 29,654 from ischemic heart disease (IHD)], 18,090 from cerebrovascular diseases, and 29,033 incident cases of stroke. Residential greenness, expressed as interquartile range (IQR) increase in LAI within 300 m, was inversely associated with stroke incidence {hazard ratio (HR) 0.977 [95% confidence interval (CI): 0.961, 0.994]} and mortality for nonaccidental [HR 0.988 (95% CI: 0.981, 0.994)], cardiovascular [HR 0.984 (95% CI: 0.974, 0.994)] and cerebrovascular diseases [HR 0.964 (95% CI: 0.943, 0.985)]. Similar results were obtained using NDVI with 300- or 1,000-m buffers.Conclusions:Living in greener areas was associated with better health outcomes in our study, which could be partly due to reduced exposure to environmental hazards. Further research is required to understand the underlying mechanisms. https://doi.org/10.1289/EHP2854
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