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Delirium is sudden severe confusion and rapid changes in brain function that occur with physical or mental illness.
Acute confusional state; Acute brain syndrome
Causes, incidence, and risk factors
Delirium is most often caused by physical or mental illness and is usually temporary and reversible. Many disorders cause delirium, including conditions that deprive the brain of oxygen or other substances.
- Changes in alertness (usually more alert in the morning, less alert at night)
- Changes in feeling (sensation) and perception
- Changes in level of consciousness or awareness
- Changes in movement (for example, may be slow moving or hyperactive)
- Changes in sleep patterns, drowsiness
- Confusion (disorientation) about time or place
- Decrease in short-term memory and recall
- Unable to remember events since delirium began (anterograde amnesia)
- Unable to remember events before delirium (retrograde amnesia)
- Disrupted or wandering attention
- Inability to think or behave with purpose
- Problems concentrating
- Disorganized thinking
- Speech that doesn't make sense (incoherent)
- Inability to stop speech patterns or behaviors
- Emotional or personality changes
- Movements triggered by changes in the nervous system (psychomotor restlessness)
Signs and tests
The following tests may have abnormal results:
- An exam of the nervous system (neurologic examination), including tests of feeling (sensation), thinking (cognitive function), and motor function
- Neuropsychological studies
The following tests may also be done:
- Ammonia levels in the blood
- Blood chemistry (comprehensive metabolic panel)
- Blood gas analysis
- Chest x-ray
- Cerebrospinal fluid (CSF) analysis
- Creatine kinase level in blood
- Drug, alcohol levels (toxicology screen)
- Electroencephalogram (EEG)
- Head CT scan
- Head MRI scan
- Liver function tests
- Mental status test
- Serum magnesium
- Thyroid function tests
- Vitamin B1 and B12 levels
The goal of treatment is to control or reverse the cause of the symptoms. Treatment depends on the condition causing delirium. The person may need to stay in the hospital for a short time.
Stopping or changing medications that worsen confusion, or that are not necessary, may improve mental function. Substances and medicines that can worsen confusion include:
- Analgesics, especially narcotics such as codeine, hydrocodone, morphine, or oxycodone
- Central nervous system depressants
- Recreational drugs
Disorders that contribute to confusion should be treated. These may include:
- Decreased oxygen (hypoxia)
- Heart failure
- High carbon dioxide levels (hypercapnia)
- Kidney failure
- Liver failure
- Nutritional disorders
- Psychiatric conditions (such as depression)
- Thyroid disorders
Treating medical and mental disorders often greatly improves mental function.
Medicines may be needed to control aggressive or agitated behaviors. These are usually started at very low dosages and adjusted as needed:
- Antidepresssants (fluoxetine, citalopram), if depression is present
- Dopamine blockers (haloperidol, quetiapine, or risperidone are most commonly used)
- Sedatives (clonazepam or diazepam) in cases of delirium due to alcohol or sedative withdrawal
Some people with delirium may benefit from hearing aids, glasses, or cataract surgery.
Other treatments that may be helpful:
Delirium often lasts only about 1 week, although it may take several weeks for mental function to return to normal levels. Full recovery is common.
Calling your health care provider
Call your health care provider if there is a rapid change in mental status.
Treating the conditions that cause delirium can reduce its risk. In hospitalized patients, avoiding sedatives, staying still (immobilization), and bladder catheters, and using reality orientation programs will reduce the risk of delirium in those at high risk.
Mendez MF, Kremen SA. Delirium. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley’s Neurology in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 4.
Rudolph JL, Marcantonio ER. Delirium. In: Duthie EH Jr., Katz PR, Malone ML. Practice of Geriatrics. 4th ed. Philadelphia, PA: Elsevier Saunders; 2007:chap 26.
Reviewed By: Luc Jasmin, MD, PhD, Department of Neurosurgery, Cedars Sinai Medical Center, Los Angeles and Department of Anatomy, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.