Abstract
At the threshold of the millenium the industrial countries have to face the problem of an increasingly aged population. Between 1900 and 1980 the life expectancy per person at age 65 has risen from 11.9 years to 16.4 years. During the 1980s the number of people aged 75–79 increased by 28.8% and that of persons over the age of 85 years by 52.4% [1]. It should be pointed out that not only has the life expectancy of older persons improved, but also their general health status is substantially better than in the past. The longevity revolution will continue to increase in the future and will represent a major problem for politicians, economists, and sociologists.