Introduction

In most fields of medical research interest was formerly directed mainly towards diseases occurring before old age. Not least was this the case in the domains of psychiatry and human genetics. During the last few decades, however, the study of the diseases of old age and, in general, the various problems confronting old people have attracted increasing attention. This applies above all to the countries of the West, where demographic, economic and social developments have already brought about a striking structural change in the population. What we are here confronted with is the interaction between a number of factors, some of which are (cf. Sjogren & Larsson 1959) :