Incidence of amyotrophic lateral sclerosis and of the parkinsonism-dementia complex of Guam, 1950-1989

Studies representing the accumulated information from the first 30 years of research effort on Guam (1950-1979) have demonstrated a varying degree of decline in the incidence of amyotrophic lateral sclerosis (ALS) and the parkinsonism-dementia complex (PDC) of Guam. Analysis with more complete information for the period 1980-1989 provides more valid estimates of the later patterns in the incidence of ALS and PDC and affords a more extensive assessment of trends over a 40-year period. The annual age-adjusted incidence of ALS was 7/100,000 and the annual age-adjusted incidence of PDC was 22/100,000 in 1989. The incidence was much higher for the period 1980-1989 than suggested in previous reports. These findings provide compelling evidence that this spectrum of neurodegenerative diseases continues to have a significant impact on the health of the Chamorro people of Guam.