Patterns of Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia on Guam.

The striking concentration of amyotrophic lateral sclerosis (ALS) and parkinsonismdementia (PD) among the Chamorro people of Guam has attracted attention since the early 1950's. Extensive studies conducted over the past 20 years have not revealed the causes of these diseases and the reasons for their remarkable concentrations on Guam. Approximately 1 in 10 Guamanian deaths over age 25 is from ALS, and another 1 in 10 is from PD. ALS still occurs approximately 50 times more frequently on Guam than in the continental United States. Advances in virologic and biochemical techniques, and long years of study, appear to be leading us to a point where some of the problems will be resolved. We shall attempt to review the pertinent background information and summarize the data and observations up to the present time.