Amyotrophic lateral sclerosis in Olmsted County, Minnesota, 1925 to 1998.

The authors sought to determine trends in the incidence of ALS in Olmsted County from 1925 to 1998. Seventy-seven cases of ALS were identified during the period studied. The incidence rate remained stable at 1.7 cases per 100,000 people per year. Mean age at onset was 63 years. Mean survival was 23 months from diagnosis. Mean survival for patients <60 years old was 31 months; for patients aged >or=60 years, it was 20 months (p = 0.02). Mean time from symptom onset to diagnosis was 13 months. Neither survival nor time to diagnosis changed significantly over time.