The concept of delirium

The concept of delirium has a long and confusing history. This article outl ines the development of ideas relating to core features of the syndrome: di sturbance of consciousness, disturbance of cognition, its course and its ex ternal causation, The modern concept of delirium, and the diagnostic criter ia found in current classifications are based upon a long tradition of clin ical observation in younger patients, and their emphasis on positive sympto ms and identifiable external causes may not be applicable to our ageing pop ulation.