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Frontotemporal dementia: Epidemiology, pathology, and pathogenesis

Suzee E Lee, MD
Bruce L Miller, MD
Section Editor
Steven T DeKosky, MD, FAAN, FACP, FANA
Deputy Editor
Janet L Wilterdink, MD


Frontotemporal dementia (FTD) is a clinically and neuropathologically heterogeneous disorder characterized by disturbances in behavior, personality and language accompanied by focal degeneration of the frontal and/or temporal lobes. FTD serves as an umbrella term for several clinical syndromes, including behavioral variant FTD (bvFTD), semantic variant primary progressive aphasia (svPPA), and nonfluent variant primary progressive aphasia (nfvPPA).

The term frontotemporal lobar degeneration (FTLD) is used commonly to denote the pathologic diagnoses associated with the clinical FTD spectrum. FTLD can be subdivided according to the nature of the characteristic cytoplasmic or nuclear protein inclusions that are observed histopathologically. In general, there is inconsistent correlation between clinical FTD syndromes and the underlying pathologic subtypes, which poses a challenge to the development and testing of therapies designed to target specific protein dysfunction in neurodegeneration. There is also increasing recognition of significant pathologic and genetic overlap between motor neuron disease and FTLD, as well as other neurodegenerative disorders.

This topic will review the epidemiology, pathogenesis and pathology of FTLD. The clinical manifestations, diagnosis and treatment of FTD are discussed separately. (See "Frontotemporal dementia: Clinical features and diagnosis" and "Frontotemporal dementia: Treatment".)


Frontotemporal dementia (FTD) is one of the more common causes of early-onset (midlife) dementia, occurring at similar frequency to Alzheimer disease (AD) in patients younger than 65 years. In a population-based study of early-onset dementia in Cambridgeshire, England, the incidence of FTD was estimated to be 3.5 cases per 100,000 person-years in adults aged 45 to 64 years, while the incidence of AD in the same age range was 4.2 per 100,000 person-years [1]. Another study found an estimated prevalence of 15 cases per 100,000 for both FTD and AD in the 45 to 64 year age range [2]. Since many FTD patients present with behavioral changes, it has been suggested that estimates of incidence and prevalence are conservative, since a subset of patients is likely to be referred to psychiatric services [2].

The mean age of onset of FTD is about 58 years [3-8]. The reported age of onset has ranged from 20 to 80 years, although onset before 40 or after 75 years of age is unusual.

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Literature review current through: Nov 2017. | This topic last updated: Mar 30, 2017.
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