What Is Delirium?

Is It Delirium or Dementia?

Question: What Is Delirium?

Delirium is characterized by a rapid onset of changes in consciousness and cognition. It's caused by an acute (brief yet severe) medical condition that either disrupts brain metabolism or brain chemistry, both of which can significantly affect brain functioning.

Diagnosing delirium is complicated because it often occurs alongside at least one chronic condition with some overlapping symptoms.

For example, memory problems and confusion are symptoms of both Alzheimer's and delirium, and these two conditions frequently occur together in hospital settings. In fact, Alzheimer's and other kinds of dementia are actually risk factors for delirium.

While delirium does not always occur in a hospital, it almost always requires hospitalization. Nursing homes are another common environment where delirium is found.

Symptoms of Delirium

People with delirium display fluctuations in consciousness, such as a reduced awareness of one's surroundings or severe attention problems. There are also changes in cognition such as problems with memory, orientation, language, or perception that can't be better explained by dementia. Most importantly, the symptoms develop over a short period of time -- such as hours or days -- and the symptoms vary throughout the day.

Diagnosis and Treatment of Delirium

Unlike Alzheimer's and other kinds of dementia, delirium doesn't usually involve structural brain damage.

Therefore, instead of using imaging procedures to identify brain abnormalities, delirium is usually diagnosed by conducting a thorough medical history, physical exam, and laboratory tests to pinpoint the cause of the symptoms. Three common causes of delirium include:

  • General Medical Conditions -- Examples of medical conditions that can cause delirium include urinary tract infections, meningitis, endocrine disorders, hypothermia, electrolyte imbalances, and heat stroke.
  • Substance Intoxication or Interaction -- This refers to both intentional and unintentional substance intoxication or medication interactions.
  • Substance Withdrawal -- This occurs shortly after a withdrawal syndrome from alcohol, an illegal substance, prescription medications, and/or over-the-counter drugs.

Delirium can also result from a combination of these factors. The appropriate method of treatment for delirium depends fully upon its cause. Quick and accurate treatment is essential, because some deliriums -- if left untreated -- can cause permanent brain damage or even death.

Prognosis for Delirium

If the cause of delirium is properly identified and treated, it often lasts less than one month from the onset of symptoms to the time of recovery. However, an episode of delirium may last only a few hours, or it might persist for weeks depending on its cause, identification, and treatment. Delirium in the presence of Alzheimer's disease or another dementia often lasts longer than delirium when it occurs alone.


American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.

Mace, N. L., & Rabins, P. V. (2006). The 36-Hour Day: A Family Guide to Caring for People with Alzheimer Disease, Other Dementias, and Memory Loss in Later Life (4th Ed.). Baltimore, MD: Johns Hopkins University Press.

Zarit, S. H., & Zarit, J. M. (1998). Mental disorders in older adults: Fundamentals of assessment and treatment. New York: The Guilford Press.