The Classification, Genetics and Neuropathology of Frontotemporal Dementia. Introduction to the Special Topic Papers: Part I

Abstract

Interest in the neuropsychology and neuropsychiatry of frontotemporal dementia (FTD) has escalated in the past decade, as evidenced by the accompanying 10 special topic papers from research groups in the UK, France, North America and Australia addressing a wide range of theoretical and clinical issues. The first part of this review deals with the confusing terminologies that have been used in the area and argues for the retention of the term FTD as the general clinical label, with further subcategorization into the three principal clinical syndromes seen at presentation: frontal variant FTD (often called dementia of frontal type), semantic dementia and progressive non-fluent aphasia. Each of these syndromes has a characteristic profile of presenting clinical features, but may be accompanied by any one of five types of non-Alzheimer pathological change. There have also been significant advances in the genetics of FTD with the identification of tau gene mutations on chromosome 17 in some familial cases. The remarkable story of the discovery of these, the tau gene mutations, is briefly described. Part II of this review (Hodges and Miller, 2001) sets the special issue papers within the context of advances in the neuropsychology of frontal variant FTD and semantic dementia.

A Neurocomputational Model of Analogical Reasoning and its Breakdown in Frontotemporal Lobar Degeneration

“…These experiments were performed with patients diagnosed with frontotemporal lobar degeneration (FTLD). FTLD is a regional neurodegenerative etiology of dementia distinct from Alzheimer's disease (e.g., Hodges & Miller, 2001;Neary et al, 1998). Based on clinical features and neuroimaging (see Figure 1), FTLD patients can be divided based on their primary locus of damage.…”

“…Based on clinical features and neuroimaging (see Figure 1), FTLD patients can be divided based on their primary locus of damage. Frontal lobe FTLD patients typically present with behavioral disturbances and have damage to the orbital medial regions of the prefrontal cortex, which extends into the dorsolateral prefrontal cortex and inferior frontal gyrus as the disease progresses (Hodges & Miller, 2001). Temporal lobe FTLD presents with a loss of conceptual knowledge, fluent aphasia, and late emotional changes.…”

“…Temporal lobe FTLD presents with a loss of conceptual knowledge, fluent aphasia, and late emotional changes. Damage is most apparent in the anterior temporal cortex (Hodges & Miller, 2001). Studies of FTLD patients can provide a useful complement to neuroimaging studies by making it possible to investigate the global roles of frontal and anterior temporal lobes in reasoning.…”

Progressive language impairments: Definitions, diagnoses, and prognoses

“…This behavioural variant of frontotemporal dementia (also called frontal variant frontotemporal dementia; Hodges & Miller, 2001) will not be addressed in detail in this paper. However, behaviour changes do often emerge with progression in cases of progressive aphasia, (as neuropathology spreads to brain regions responsible for these functions), so these will be discussed in relation to disease progression and prognosis.…”

“…Semantic dementia, according to the early definitions (Hodges, Patterson, Oxbury, & Funnell, 1992;Snowden et al, 1989), is characterised by striking anomia and impaired word comprehension attributed to loss of semantic memory (e.g., concepts, facts, semantic features) (Hodges & Miller, 2001;Knibb et al, 2006). As noted by Snowden et al (1989), these semantic memory deficits also impair recognition of visually presented objects, a symptom known as visual agnosia (Neary, 1999).…”