[Where fronto-temporal dementia should be placed in the history of Pick's disease and related disorders].

Pick syndrome, non-Alzheimer type dementia with primary degeneration in the anterior portion of the brain, has been shown to include several disease-entities besides classic Pick's disease. Fronto-temporal dementia (FTD) proposed by Lund & Manchester group is a concept that includes Pick's disease, and its "clinical diagnostic features" are useful because they distinguish dementia with frontal and anterior temporal involvement from Alzheimer type dementia. FTD is classified into three types, the frontal lobe degeneration (FLD) type, Pick type and motor neuron disease (MND) type, and neuropathological diagnostic features of each type are presented. In Japan, however, cases neuropathologically corresponding to the FLD type, which has mild frontal dominant degeneration with heavy heredity, have not been previously reported. Classic Japanese Pick's disease is consistent with Pick type, however, cases of Pick's disease with and without Pick body exist in nearly the same number in Japan. The latter may include heterogeneous types, which should be elucidated. MND type corresponds to Japanese cases, called Yuasa-Mitsuyama disease or dementia with motor neuron disease, and could be actually diagnosed because such patients do not exhibit severe personality change and accompany symptoms of amyotrophic lateral sclerosis or spinal progressive muscular atrophy in their clinical course. In addition, Pick syndrome includes progressive subcortical gliosis, corticobasal degeneration, basophilic inclusion body disease and fronto-temporal dementia with parkinsonism linked chromosome 17. Progressive aphasia and semantic dementia are neuropsychologically important concepts, however, they are symptom-complex and are dominated only by where the degeneration begins and how it progresses. They should not be confused with pathologically confirmed disease-entities.