Neurofibrillary change on Guam.

Distribution and occurrence of neurofibrillary change (NFC) in the brain were studied in 114 Guamanians who had neither amyotrophic lateral sclerosis (ALS) nor parkinsonism dementia (PD). Comparison was made with 28 Guamanians with ALS-PD and 53 non-Guamanians without ALS-PD. Search for NFC was made in 15 dogs and cats that lived on Guam. Most of the Guamanians without ALS-PD during and after middle age had NFC similar to that of Guamanians with ALS-PD but lesser in degree and extent of involvement. It is possible that the general population of Guam had been exposed to the unknown etiologic agent of ALS-PD during some previous period.