Changes in the clinical features of amyotrophic lateral sclerosis in rural Japan

To assess longitudinal changes in the clinical features of patients with amyotrophic lateral sclerosis (ALS), we performed a retrospective hospital-based study covering 35 years.

We investigated 287 patients (154 men and 133 women) with sporadic ALS hospitalized at the Department of Neurology at Gunma University Hospital (Japan) between 1978 and 2012. All patients fulfilled the diagnostic criteria for definitive, probable or laboratory-supported probable ALS according to the revised El Escorial criteria.

Two hundred patients (69.7%) exhibited limb onset and 87 patients (30.3%) exhibited bulbar onset of the disease. The percentage of patients who showed bulbar onset of the disease increased steadily over the 35 years from 14.2% (1978-82) to 38.3% (2008-12) (p<0.01, r=0.470). The mean age at onset was 62.1 ± 11.7 years, and the age at onset increased significantly over time from 51.7 years (1978-82) to 64.9 years (2008-12) (p<0.001, r=0.294). In addition, the percentage of patients whose age at onset was 70 years or more increased from 0% (1978-82) to 38.2% (2008-12). The percentage of ALS patients with dementia increased from 0% (1978-82) to 20.2% (2008-12).

Our findings demonstrate that, among patients with sporadic ALS, the age at disease onset, the proportion of patients with disease onset at 70 years of age or higher, the proportion of patients with dementia and the proportion of patients with bulbar onset ALS have increased significantly over the past 35 years. The longitudinal changes observed in the clinical features of ALS may reflect the increasing age at disease onset.