What is successful ageing and who should define it?

The substantial increases in life expectancy at birth achieved over the previous century, combined with medical advances, escalating health and social care costs, and higher expectations for older age, have led to international interest in how to promote a healthier old age and how to age "successfully." Changing patterns of illness in old age, with morbidity being compressed into fewer years and effective interventions to reduce disability and health risks in later life, make the goal of ageing successfully more realistic. Debate continues about whether disability has been postponed, although the Berlin ageing study and the US MacArthur study of ageing showed that greater longevity has resulted in fewer, not more, years of disability. A forward looking policy for older age would be a programme to promote successful ageing from middle age onwards, rather than simply aiming to support elderly people with chronic conditions. But what is successful ageing? And who should define it?