Long considered to be a disorder restricted to the motor system, amyotrophic lateral sclerosis (ALS) is increasingly recognized to be syndromic, not only in its clinical manifestations but also in its biology. This comes as no surprise to neurogeneticists interested in ALS, long familiar with the concept of polygenic diseases, or with the newer field of toxicogenomics (neurotoxicology with a genetic bent to the rest of us). Nor is it a surprise to those interested in the hyperendemic foci of ALS in which the co-occurrence of ALS with dementia, and often parkinsonism, is well recognized. And to those familiar with the chromosome 17 linked ALS with frontotemporal dementia (FTD), with or with tau mutations, this again is of no surprise. The surprise to many is the extent to which cognitive impairment or dementia can be a feature of sporadic ALS.
Strong MJ. ALS—Not What We Thought. Arch Neurol. 2006;63(3):319-320. doi:10.1001/archneur.63.3.319