The classification, genetics and neuropathology of frontotemporal dementia. Introduction to the special topic papers: Part I.

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.