Temporo-spatial analysis of amyotrophic lateral sclerosis in Spain: altitude and land use as new determinants of the disease

Abstract

Introduction: Amyotrophic lateral sclerosis (ALS) is the most common neurodegenerative disease affecting motor neurons. Currently, ALS is conceived as the result of the interaction between genetics, environmental factors, and aging. This study analyzed the spatial and temporal patterns of ALS in Spain, delving into the potential relationships between altitude, land cover, and this disease. Methodology: ALS death data were collected over a 19-year period, including information on sex, age and municipality of residence. The standardized mortality rate was calculated for each municipality of residencia, and Anselin's local Moran's I statistic was used to identify clusters of high and low incidence. Altitude data were sourced from the Copernicus Land Monitoring Services, while land cover data came from CORINE satellite images and national agricultural statistics. Results: The average annual incidence of ALS deaths among adults was 2.5 per 100,000 people. Higher mortality rates were noted in males (2.8) than in females (2.3), with both sexes exhibiting a rising mortality trend in a temporal analysis. Cluster analysis revealed that high mortality areas were mostly located in the North and Northeast of the country. Municipalities in these clusters had significantly lower median altitudes and larger areas of Permanently Irrigated Arable Land and Broad-Leaved Forest. Conclusion: This study provides new evidence about the increase in ALS cases in European countries during the last decades, reporting for the first time altitude and certain agricultural land uses as potential geographic determinants of the disease.