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(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 insanityinsanity,
mental disorder of such severity as to render its victim incapable of managing his affairs or of conforming to social standards. Today, the term insanity is used chiefly in criminal law, to denote mental aberrations or defects that may relieve a person from the legal
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, and the term dementia praecox was used in the 19th cent. to describe the condition now known as schizophreniaschizophrenia
, group of severe mental disorders characterized by reality distortions resulting in unusual thought patterns and behaviors. Because there is often little or no logical relationship between the thoughts and feelings of a person with schizophrenia, the disorder has
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. 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).



irreversible deterioration of mental activity, manifested mainly by a decreased ability to acquire knowledge, loss of previously acquired knowledge, emotional apathy, and behavioral changes.

Dementia may be congenital (oligophrenia) or acquired. The concept of dementia usually refers to acquired dementia, that is, dementia resulting from mental disease. Clinically, dementia may be total or partial. Total dementia is characterized by an impairment of the ability to make judgments and arrive at conclusions, a sharply decreased critical attitude toward one’s condition, a loss of individual personality features, and a predominance of a complacent attitude (as in the case of senile psychosis). The main symptom of partial (dysmnestic) dementia is a disturbance of memory accompanied by emotional instability, helplessness, and a weakening of mental activity (as in the case of vascular disease of the brain). In partial dementia, however, consciousness of one’s own incompetence is retained, and the personality does not lose its individuality to the degree that it does with total dementia. The irreversibility of dementia is to some extent conditional, as is demonstrated by the results of treatment for patients with Bayle’s disease. In addition, there is a special form of acute transitory dementia associated with certain febrile, toxic, and other psychoses. The characteristics of dementia depend on the disease that produces the mental deterioriation; among the diseases are epilepsy, schizophrenia, and alcoholism.



Deterioration of intellectual and other mental processes due to organic brain disease.


a state of serious emotional and mental deterioration, of organic or functional origin
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