A new theory of the dementing process in old age is presented in outline. Its main focus is on the dialectical interplay between neurological and social-psychological factors, with special emphasis on aspects of the latter which deprive a neurologically impaired individual of his or her personhood. The account of dementia so derived is more comprehensive and less deterministic than those which are based on the simpler versions of a ‘medical model’. Also, it opens up the way for a more personal and optimistic view of caregiving.