1806, from Latin dementia "madness, distraction, folly," noun of state from dementem, from dementer (see dement). It existed earlier in an anglicized form, demency (1520s), from French démence. Dementia praecox is a Modern Latin form recorded from 1899 in English, 1891 in German, from French démence précoce (1857). See precocious.
Deterioration of intellectual faculties, such as memory, concentration, and judgment, resulting from an organic disease or a disorder of the brain, and often accompanied by emotional disturbance and personality changes.
Deterioration of intellectual faculties, such as memory, concentration, and judgment, sometimes accompanied by emotional disturbance and personality changes. Dementia is caused by organic damage to the brain (as in Alzheimer's disease), head trauma, metabolic disorders, or the presence of a tumor.
