Long-Term Air Pollution Exposure and Amyotrophic Lateral Sclerosis in Netherlands: A Population-based Case control Study

BACKGROUND: Recently, there has been increasing evidence that exposure to air pollution is linked to neurodegenerative diseases, but little is known about the association with amyotrophic lateral sclerosis (ALS). OBJECTIVES: We investigated the association between long-term exposure to air pollution and risk of developing ALS. METHODS: A population-based case-control study was conducted in Netherlands from 1 January 2006 to 1 January 2013. Data from 917 ALS patients and 2,662 controls were analyzed. Annual mean air pollution concentrations were assessed by land use regression (LUR) models developed as part of the European Study of Cohorts for Air Pollution Effects (ESCAPE). Exposure estimates included nitrogen oxides (NO2, NOx), particulate matter (PM) with diameters of <2.5 mu m (PM2.5), <10 mu m (PM10), between 10 mu m and 2.5 mu m (PMcoarse), and PM2.5 absorbance. We performed conditional logistic regression analysis using two different multivariate models (model 1 adjusted for age, gender, education, smoking status, alcohol use, body mass index, and socioeconomic status; model 2 additionally adjusted for urbanization degree). RESULTS: Risk of ALS was significantly increased for individuals in the upper exposure quartile of PM2.5 absorbance [OR=1.67; 95% confidence interval (CI): 1.27, 2.18], NO2 (OR=1.74; 95% CI: 1.32, 2.30), and NOx concentrations (OR=1.38; 95% CI: 1.07, 1.77). These results, except for NOx, remained significant after adjusting additionally for urbanization degree. CONCLUSIONS: Based on a large population-based case-control study, we report evidence for the association between long-term exposure to traffic-related air pollution and increased susceptibility to ALS. Our findings further support the necessity for regulatory public health interventions to combat air pollution levels and provide additional insight into the potential pathophysiology of ALS.