[Amyotrophic lateral sclerosis-parkinsonism-dementia complex of the Kii Peninsula of Japan].

The Hohara village of the Kii peninsula is one of the high incidence ALS foci, and the high incidence was reported to have ended in early 1980s. However, we have found the ALS incidence rate has been still high, more than 100 times of the other areas of Japan. In addition, we have found many cases of parkinsonism-dementia complex (PDC). ALS and PDC often occur simultaneously in a single patient or in a single family. Family history was positive in more than 70% of patients. ALS and PDC showed common neuropathological findings consisting of ALS pathology and many neurofibrillary tangles (NFT) without senile plagues, and isoform pattern of NFT tau protein was similar to that of Alzheimer disease (AD), but different from that of progressive supranuclear palsy (PSP) or Pick's disease (PiD). Kii ALS/PDC may be a novel tauopathy that differ from AD, PSP or PiD.