Dementia

Dementia is not a single disease but a group of cognitive disorders typically characterized by memory impairment, personality changes, and impaired reasoning.
Affected cognitive areas can be memory, attention, language, and problem solving.
Generally, symptoms must be present for at least six months to support a diagnosis .
Cognitive dysfunction of shorter duration is called delirium. The diagnosis of dementia is generally made with demonstrable evidence of impairment of memory or intellectual functioning. Dementia can be classified as either reversible or irreversible depending upon the etiology of the disease.