Among the more frequently quoted epidemiological facts in current public health discussions are: (a) the elderly today represent about 10% of the population of the industrialized world; (b) the third world nations are moving in the same direction; (c) the trend toward a growing proportion of the aged in the world population will continue over the next few decades; (d) people over 80 now represent the fa. stest growing sector in North America; (e) in the elderly, general morbidity - and particularly morbidity of the central nervous syste- is many times that in the younger popUlation; (f) 5% of...