ABSTRACT
Improvements in life style and progress in medicine have been responsible for a large increase of life expectancy during the last two centuries. Today, in developed countries, people live much longer than they did in previous eras. In France, for example, the life expectancy before the French revolution (1789) was less than 30 years. It reached 50 years in 1900 and has consistently improved since that period. Today it is above 80 years. In underdeveloped countries, the life expectancy is lower and can be of the order of 40 years in the poorest countries or in those where large segments of the populations are faced with a diseases such as AIDS or alcoholism, for example. As populations become older deaths due to chronic diseases increase. About 80% of seniors have at least one chronic disease and 50% have at least two. In the United-States 70% of all deaths are due to chronic diseases. Technological advances such as those offered by nanotechnology can have far reaching consequences in healthcare.
