Temporal trend of amyotrophic lateral sclerosis incidence in southern Europe: a population study in the health district of Ferrara, Italy.

Data about the temporal trend of amyotrophic lateral sclerosis (ALS) incidence in southern Europe are scarce. Incidence studies on ALS have been carried out in the health district of Ferrara, Italy, since 1960s. We expanded the previous studies from 1964 to 2009. The study was prospective with subsequent retrospective intensive survey of multiple sources of case ascertaiment. The present findings do not support the role of specific environmental factors in ALS pathogenesis