Associations between level of urbanization and greenness and the development of amyotrophic lateral sclerosis: A...

Previous studies have considered level of urbanization when evaluating the role of place of residence in ALS. However, these studies have been subject to recall bias regarding previous exposures to urban characteristics owing to a lack of historical geospatial measures on urban form indicators.

Thus, we created a robust database from multiple sources and conducted a matched case-control study in New Brunswick, Canada to investigate the association between long-term exposure to various local climate zones, as well as greenness, at place of residence and the development of ALS.

Odds of ALS were not significantly associated with the dense urban (1.1, 0.6 - 2.0 [95% CI]), open urban (0.5, 0.2 - 1.3 [95% CI]), residential (1.0, 0.9 - 1.1 [95% CI]), industrial (0.8, 0.6 - 1.2 [95% CI]), natural (1.0, 0.9 - 1.1 [95% CI]), or water (1.0, 0.9 - 1.1 [95% CI]) local climate zone classification categories per ten percentage increase in influence in the adjusted regression models. Exposure to greenness (1.7, 0.5 - 6.2 [95% CI]) was also not significantly associated to ALS in the adjusted regression models.

While not significantly associated to ALS, urban influence and greenness need to be further explored. Future studies should consider traffic-related pollutants as it pertains to urban density, while considering vegetation type and industry practices, such as farming and spraying, alongside greenness exposure measures.