The evolution and pathology of frontotemporal dementia

This is a clinicopathologic study of a prospective, clinic-based cohort of patients with frontotemporal dementia (FTD)/Pick complex, who were followed to autopsy. A total of 60 patients with the clinical syndromes of the behavioural variant of FTD (FTD-bv) (n = 32), primary progressive aphasia (PPA) (n = 22), corticobasal degeneration syndrome (CBDS) (n = 4) and progressive supranuclear palsy (PSP) (n = 2) at onset, referred to a cognitive neurology clinic who had subsequent post-mortem examination were included. The most common histological variety was motor neurone disease type inclusion (MNDI) (n = 18), followed by corticobasal degeneration (CBD) (n = 12), then Pick's disease (n = 6), dementia lacking distinctive histology (DLDH) (n = 6) and PSP (n = 3). Others fulfilled the histological criteria for Alzheimer's disease combined with glial pathology (n = 6), Alzheimer's disease only (n = 4), Lewy body variant (n = 2), prion disease (n = 1), vascular dementia (n = 1) and undetermined (n = 1). The most common first syndrome among the MNDI and DLDH (tau negative) pathologies was FTD-bv, but subsequently progressive aphasia (PA), occasionally CBDS and semantic dementia also developed. Tau positive histologies of CBD, PSP and Pick bodies were most frequently associated with PPA onset or CBDS/PSP, but behavioural symptoms were also common. Age of onset was earlier in tau negative cases, but the duration of illness and gender distribution were about the same in all histological variants. Although the tau negative and positive histologies are predicted to some extent by the clinical onset, the extent of the overlap and the convergence of the syndromes in the course of the disease argue in favour of maintaining the clinical and pathological varieties under a single umbrella.