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Pronunciations dementia

Delirium and dementia are the most common causes of mental (cognitive) dysfunction—the inability to acquire, retain, and use knowledge normally. Although delirium and dementia may occur together, they are quite different. Delirium begins suddenly, causes fluctuations in mental function, and is usually reversible. Dementia begins gradually, is slowly progressive, and is usually irreversible. Also, the two disorders affect mental function differently. Delirium affects mainly attention. Dementia affects mainly memory. Both delirium and dementia may occur at any age but are much more common among older people because of age-related changes in the brain (see Biology of the Nervous System: Effects of Aging).

Comparing Delirium and Dementia Feature Delirium Dementia Development Sudden, sometimes with a definite beginning point Slow, with an uncertain beginning point Cause Almost always another condition, such as an infection, dehydration, or use or stopping of certain drugs Usually a brain disorder, such as Alzheimer's disease, vascular dementia, or Lewy body dementia Main early symptom Inability to pay attention Loss of memory, especially recent events Effect at night Almost always worse Often worse Level of alertness (consciousness) Impaired to varying degrees, can vary from being hyperalert to sluggish Normal until late stages Orientation to surroundings Varies Impaired Effect on language Slowed speech, often with incoherent and inappropriate language Sometimes difficulty finding the right word Memory Varies Lost, especially for recent events Progression Causes variations in mental function people are alert one moment and sluggish and drowsy the next Slowly progresses, gradually but eventually greatly impairing all mental functions Duration Days to weeks, sometimes longer Almost always permanent Need for treatment Immediate Needed but less urgently Effect of treatment Usually reverses the losses May slow progression but cannot reverse or cure the disorder

Last full review/revision February 2008 by Juebin Huang, MD, PhD