Ask people about ageing in our society, and everyone has a view. Most would think it widely known that older age is a time of declining mental and physical function, worse health, and economic and social dependency. Indeed, a small number of people over the age of 65 fit this stereotype. Most do not. What is striking about the health and social circumstances of older people in society is how variable the picture is, ranging from this rather depressing stereotype to that of vigorous octogenarians, economically and socially independent, with little disability, wide social and cultural interests and much to contribute to society.
It is precisely to understand this variability that the English Longitudinal Study of Ageing (ELSA) was established. It has three principal purposes. Firstly, to complete the picture of what it means to grow older in the new century. Surprisingly, the range of pictures painted in this report has hitherto been available only in partial form. There has been much concern with pensions, but little information on who has what financial arrangements for retirement; much concern with increasing disability, but sparse data on the range of positive functions with increasing age; worry over increasing social isolation of older people, but little evidence on who is doing what at older ages. Completing the picture means going into detail. It is not sufficient to know that mental functions decline with age; it is important to know which functions. It is not enough to know that people's physical functions decline with age; it is important to know how that decline varies depending on gender, occupational career and circumstances in later life.
This leads to a second principal purpose of ELSA, which is to examine the interrelationship between different areas of life. What is the relationship, for example, between health and adequacy of financial arrangements for older age? How does social status relate to the quality of the social environment? Why do people in lower social positions appear to be suffering from agerelated declines at an earlier age than people in higher social positions? How does the nature of pension arrangements affect people's continued participation in the workplace? How does cognitive function influence people's ability to plan for their financial future? By bringing together scientists from different disciplines and gathering high-quality information on these different 'domains' of life, ELSA provides a resource that is unique in Britain.
The third purpose of ELSA is understanding. What accounts for the variety of patterns that we see? The aim here is, very clearly, to provide the scientific basis for policy. What determines whether old age will be a time of misery and dependency, or one of vigour, social engagement and good health? Which of these pictures, and the whole range in between, will dominate has profound import for social and medical services, for the economy and for the design of neighbourhoods, as well as for the well-being of the population.