Frontotemporal dementia or frontotemporal lobar degeneration--overview of a group of proteinopathies.

Frontotemporal dementia is the second most common early onset dementia after Alzheimer disease. Frontotemporal dementias are a complex group of dementias. The clinical diagnosis can be perplexing because of concurring psychiatric and neurologic syndromes. Frontotemporal lobar degeneration, the underlying pathology, represents an emerging group of proteinopathies. Genetic factors play an important part in the etiologies of dementias. This article overviews current defining characteristics of frontotemporal dementias known also as frontotemporal lobar degenerations.