The purpose of this study is: 1) to investigate the genetic and epidemiological factors contributing to the very high incidence of Amyotrophic Lateral Sclerosis and Parkinsonism Dementia (ALS/PD) on Guam; 2) To evaluate the distribution of the various estalished genetic and anthropological markers among the normal Guamanian population and compare them with those of the ALS/PD patients; and 3) to acertain the effects of immobilization due to paralysis on bone density.