The epidemiology of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease in adults and is characterized by neurodegeneration of motor neurons in the brain and spinal cord. The incidence of ALS is approximately 1-2.6 cases per 100 000 persons annually, whereas the prevalence is approximately 6 cases per 100 000. The average age of onset of ALS is currently 58-60 years and the average survival from onset to death is 3-4 years. Between October 19, 2010 and December 31, 2011, there were an estimated 12 187 prevalent cases diagnosed with definite ALS in the USA alone. Sporadic ALS (90-95%) constitutes the large majority of cases, while the remaining 5-10% are hereditary and termed familial ALS. Sporadic ALS is suspected to involve genetic susceptibility to environmental risk factors. The purpose of this review is to present a clinical overview of ALS and provide an epidemiologic summary of personal and environmental risk factors shown to be related to the risk of disease. A discussion of the most recent research initiatives is also included.