Amnesia

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Amnesia, loss or impairment of memory. Amnesia is usually associated with some form of brain damage, but it may also be caused by severe psychological trauma. Amnesia with a physical cause is called organic amnesia, whereas amnesia of psychological origin is called functional amnesia.

Amnesia varies in its degree of severity. For example, a mild concussion may cause a person to forget recent events, but the memory loss may last only for several hours. On the other hand, severe head injuries may lead to permanent memory loss and an inability to learn new information. Amnesic individuals may retain normal cognitive abilities in other areas, such as language.

Anterograde amnesia is impairment in the ability to lay down new memories. It typically results from damage to the areas of the brain involved in long-term memory, including the hippocampus, the temporal lobes, and the frontal lobes. Such damage may result from brain infection (encephalitis), alcoholism, stroke, anoxia (severe oxygen deprivation), or head injury. An individual with severe anterograde amnesia might spend an entire day with a person and then, within a brief time, totally fail to recognize that person. Retrograde amnesia refers to difficulties in recalling or recognizing past events and experiences. It typically accompanies anterograde amnesia and is especially common following concussive head injury. A person with retrograde amnesia has trouble remembering recent events, events from further in the past, or both.

Amnesia is a symptom rather than a disease, and treatment attempts to determine and remove the basic cause. No treatments available will bring back the memory capacity of brain-damaged patients. However, these patients can be helped to make better use of their remaining memory skills. The most effective methods rely on memory aids, ranging from simple devices such as notebooks and timers to computer-based organizers and paging systems. Given such help, a severely amnesic person may be able to live independently.

See also Memory.

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