Progress in clinical neurosciences: Frontotemporal dementia-pick's disease.

Frontotemporal dementia (clinical Pick's disease) is a relatively common, but underdiagnosed degenerative disease in the presenium. Estimated prevalence ranges from 6-12% of dementias. The behavioural, aphasic and extrapyramidal presentations are labeled FTD-behavioural variant, Primary Progressive Aphasia (PPA) and Corticobasal Degeneration/Progressive Supranuclear Palsy (CBD/PSP). The diagnostic features and course of each are described and their overlap in the evolution of the illness is emphasized. The neuropathology ranges from the most common tau negative ubiquitin positive amyotrophic lateral sclerosis (ALS) type inclusions to the tau positive classical Pick bodies and more or less distinct changes of PSP and CBD. The genetics of the relatively frequent tau mutations and the yet unsolved problem of tau negative families are discussed. The tau negative cases tend to be associated with the behavioural presentation and semantic dementia and the tau positive ones with PPA and the CBD/PSP syndrome. However the overlap is too great to split the disease. A glossary to navigate the proliferating terminology is included.