P3-146: Marked increase of parkinsonism-dementia (P-D) phenotypes in the high incidence amyotrophic lateral sclerosis (ALS) focus in the Kii peninsula of Japan

Abstract

A small village in the southern coast of the Kii peninsula of Japan, with a population of 1,400 is one of the high incidence ALS focus together with Guam. Marked increase of Mariana dementia in contrast to marked decline of ALS and P–D have been reported in Chamorros on Guam. To review the recent epidemiology of ALS–parkinsonism–dementia syndrome in the Kii peninsula ALS focus in Japan. 34 cases of ALS–parkinsonism–dementia (14 men and 20 women) including 6 autopsy cases, in that the onset of the disease was in 1985 or later were analyzed. Clinical phenotypes included 7 cases of pure ALS (20.6%), 6 cases of ALS plus dementia (17.6%) consisting of ALS–dementia (ALS–D) and P–D superimposed by ALS, and 21 cases of P–D (61.8%) . The average ages were 56.6 +/– 4.5 years in ALS, 66.2 +/– 5.0 years in ALS plus dementia, and 66.3 +/– 8.2 years in P–D. Family history of ALS–dementia–parkinsonism syndrome was positive in more than 75% of the patients. Neuropathologically, ALS–D and P–D showed similar findings characterized by many neurofibrillar tangles (NFTs) and ALS pathology, while pure ALS phenotype cases showed typical ALS pathology and NFTs of mild to moderate degree, suggesting that these phenotypes are of the same entity. In contrast to the marked decline of ALS/P–D on Guam, the incidence rates of ALS/P–D remain unchanged for these 50 years in the Kii peninsula ALS focus, suggesting some genetic factor may be the primary cause. ALS–D and P–D had been very rare in the Kii ALS focus before 1980. Some environmental and socio–economical changes of the residents of the Kii ALS focus, particularly aging of the population and westernization of food may have modified the disease, and have induced marked increase of P–D and ALS–D phenotypes and mild decline of pure ALS phenotypes. More and more attention paid to the cognitive and motor dysfunctions of the old people in recent years may be another factor that has increased the incidence rates of P–D phenotypes.