[History and classification of frontotemporal lobar degeneration]

The history and classification of frontotemporal lobar degeneration (FTLD) are reviewed in this paper. After Pick's descriptions, there are confusions regarding the classification of the clinical syndromes and the underlying histological changes of frontotemporal lobe degeneration of the non-Alzheimer type. In 1994, the Lund and Manchester groups proposed clinical and neuropathological criteria for the classification of frontotemporal dementia (FTD); frontal lobe degeneration type, Pick-type, and motor neuron disease (MND) type. Ubiquitin-positive and tau-negative inclusions in the extra-motor neurons were characteristic of MND type and were first described by us. In 1996 and 1998, Neary et al. proposed the concept of FTLD to facilitate diagnosis and provide diagnostic criteria for 3 clinical syndromes associated with FTLD, namely, FTD, progressive nonfluent aphasia, and semantic dementia. In 2001, an international group of clinical and basic scientists reassessed the clinical and neuropathological criteria for the diagnosis of FTD and recommended revised neuropathological criteria for diagnosis. In 2007, Cairns et al. proposed another version of the criteria for pathological diagnosis of the neurodegenerative group of diseases termed as FTLD on the basis of the recent advances in molecular genetic, biochemical, and neuropathological studies. According to these criteria, FTLD is mainly divided into 2 groups-tauopathies and TDP-43 proteinopathies-on the basis of immunohistological methods.