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.

PCA is predominantly a dorsal stream syndrome, distinct from typical DAT, which involves occipitotemporal regions over time.

A great deal has been written about cognitive aspects of semantic dementia but little is known about the demography or prognosis. We describe these features in a consecutive series of 100 patients seen over a 17-year period; all cases were assessed and followed up in a specialist clinic. The mean age at diagnosis was 64.2 (+/-7.1) range 40-79 years, but 46 presented after age 65 and 7 after 75; a higher proportion than the existing literature might predict. Fifteen had a first-degree relative with dementia, but in seven this was almost certainly unrelated. Only two had relatives with young-onset dementia. There were no families with more than two affected members. The familial rate was estimated at between 2% and 7% (95% confidence interval 0-12%). Kaplan-Meier analyses indicated a 50% survival of 12.8 years (95% confidence interval 11.9-13.7); a more benign course than suggested by neuropathologically based studies. We were unable to identify any factors influencing survival. Of the 100, 34 have died, with pathological confirmation in 24; 18 had frontotemporal lobar degeneration with ubiquitin-positive inclusions (13 of 13 confirmed TAR DNA binding protein-43 positive), and 3 had classic tau-positive Pick bodies and 3 had Alzheimer's pathology. The age at diagnosis or death across the pathological subgroups was equivalent. Although semantic dementia has a strong statistical association with ubiquitin-positive pathology, it does not have the signature of familial frontotemporal lobar degeneration with ubiquitin-positive inclusions, notably the presence of intranuclear lentiform TAR DNA binding protein-43 inclusions. The age of onset is older than predicted and the course more slowly progressive than suggested by earlier studies of small groups of subjects.

Leukoencephalopathies are a diverse group of white matter disorders that can be difficult to diagnose. Using focused and whole-exome sequencing, Lynch et al. expand the known clinical and mutational spectrum of genetic leukoencephalopathy in adulthood, and describe the frequency and clinical and radiological phenotype of the most commonly mutated genes.

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