dementia (dĬmĕn´shə) [Lat.,=being out of the mind], progressive deterioration of intellectual faculties resulting in apathy, confusion, and stupor. In the 17th cent. the term was synonymous with insanity, and the term dementia praecox was used in the 19th cent. to describe the condition now known as schizophrenia. In recent years, the term has generally been used to describe various conditions of mental deterioration occurring in middle to later life. Dementia, in its contemporary usage, is an irreversible condition, and is not applied to states of mental deterioration that may be overcome, such as delirium. The condition is generally caused by deterioration of brain tissue, though it can occassionally be traced to deterioration of the circulatory system. Major characteristics include short- and long-term memory loss, impaired judgement, slovenly appearance, and poor hygiene. Dementia disrupts personal relationships and the ability to function occupationally. Senility (senile dementia) in old age is the most commonly recognized form of dementia, usually occurring after the age of 65. Alzheimer's disease can begin at a younger age, and deterioration of the brain tissue tends to happen much more quickly. Individuals who have experienced cerebrovascular disease (particularly strokes) may develop similar brain tissue deterioration, with symptoms similar to Alzheimer's disease and senile dementia. Other types of dementia include Huntington's disease, Parkinson's disease, and Pick's disease. Some forms of familial Alzheimer's disease are caused by specific dominant gene mutations.
See L. L. Heston and J. White, The Vanishing Mind (1991).