Characterization of amyotrophic lateral sclerosis and frontotemporal dementia.

Amyotrophic lateral sclerosis (ALS) produces progressive weakness, muscular wasting, and spasticity leading to death from respiratory failure at a median of 3 years after onset. ALS and frontotemporal dementia (FTD) overlap in both familial and sporadic cases of ALS. When both occur in families, the affected members may have only ALS, only FTD, or both. This suggests a relationship in the cause of these disorders. We investigated the frequency of ALS in FTD patients and of FTD in ALS patients and found the overlap to be more common than had previously been reported. We report the features of cognitive impairment and pattern of motor involvement in these ALS-FTD patients, and the degree of overlap in both populations.