[Analytic epidemiological information of amyotrophic lateral sclerosis]

The analytical epidemiological information on amyotrophic lateral sclerosis (ALS) is extensive and is based on case-control studies, selective patient series and few cohort studies that analyze the risk factors for the disease.

The studies found in the literature on analytical epidemiology have been reviewed in an attempt to analyze the methodology, compare their results and comment on the possible biases and confounding factors such as the different roles of the risk factors.

In spite of the extensive information available, the analytical epidemiology of ALS has still not clarified the etiological factors of the disease. This may be due to the influence of the genetic factors, but also to the variability of the methodological designs. However, the analytical factor that has the greatest consistency is that of exhibition to heavy metals. Greater physical activity or increased frequency in special situations such as is the cases from the first Gulf War could be suggested as a more than casual precipitating factor.