Dementia is a state that has implications for several groups. There are, first, those who wish to assess its nature and impact in an objective and scientific fashion, using tools of research to uncover dementia’s causes, effects, and parameters. The result has been a rapidly expanding literature in diverse disciplines: physiology, chemistry, neurology, psychology, and sociology, among others. Second, there are those professionals and caregivers who work di rectly with patients and other caregivers and who must assess and apply interventions. Third, physicians are involved in diagnosis and treatment (so far as possible) and are responsible for communicating the ominous meanings of the destructive disease process. Fourth, there are the caregivers, who accept accountability for the future of a human who increasingly shows a robbing of the mind in his or her behaviors. The needs and stresses of those who care for and about those with progressive dementia are among the most intense imaginable. They need support of many kinds, frequently without knowing what to ask or of whom to ask it. Finally, there are the patients, who increasingly become dependent as their mental competencies decline. They need empathic care-including answers to questions about cause, stabilization, or reversal of the de menting process. Even more, they need cure. Further, present and future generations need the assurance of prevention. This volume surveys present knowledge about dementia and its consequences.