IT is a well-established fact that, amongst the Chamorros (native inhabitants) of Guam, there is an unduly high concentration of amyotrophic lateral sclerosis (ALS) and a form of parkinsonism with dementia (P-D). A recent study1 showed a striking clinical and histological relationship between these two syndromes which occurred in the same patients more frequently than would be expected by chance alone; also, various combinations of ALS and P-D had occurred in a number of familial aggregates.
The unique prevalence of these disorders was considered to be confined to the Chamorro population, whether living in Guam,2 in California,3 in Rota (an island approximately 30 miles north of Guam and almost exclusively populated by Chamorros), or in Saipan (about 120 miles north of Guam, four fifths of whose population is Chamorro).4 A superficial survey by Kurland and Mulder2 in 1953 of some of the neighboring Caroline Islands