The association between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is well recognised, with the majority of reports describing the behavioural form of FTD (bvFTD).1 Semantic dementia (SD) and progressive non-fluent aphasia (PNFA) have only rarely been reported alongside ALS.
Nevertheless, there have been a number of recent reports of language abnormalities in patients with ALS, with some authors arguing that they may be even more common than behavioural/executive impairments.23 Such findings raise the question of the relationship between SD and PNFA and ALS.
To date, there has been no systematic study of the relative prevalence of bvFTD, PNFA and SD in patients with and without accompanying ALS. We examined relative frequencies in a large consecutive cohort of patients with clinical forms of FTD and suspected frontotemporal lobar degeneration pathology.
We examined our clinical databases for all patients referred to a specialist dementia…