Delirium is a mental condition characterized by disorientation, confusion, uncontrolled imagination, reduced ability to focus or maintain attention, and the general inability to correctly understand immediate reality. Delirium is often accompanied by illusions, delusions, and hallucinations.

Delirium is believed to be caused by a chemical imbalance in the brain, which, in turn, may be caused by fever, drugs, improper use of medication, head injury, disease, malnutrition, illness, or other factors. The onset of delirium is usually abrupt, although the condition sometimes develops slowly, especially if a metabolic disorder is involved. Typically, delirium disappears soon after the underlying cause is successfully treated. Occasionally, however, recovery from delirium is limited by lasting neurological or other damage.

See also Attention ; Cognition ; Delusions/Delusional disorders; Hallucinations .



Caraceni, Augusto, and Luigi Grassi. Delirium: Acute Confusional States in Palliative Medicine. Oxford: Oxford University Press, 2011.

Garety, Philippa A., and David R. Hemsley. Delusions: Investigations into the Psychology Of Delusional Reasoning. Hoboken, NJ: Taylor & Francis, 2013.

Laureys, Steven, and Giulio Tononi. The Neurology of Consciousness: Cognitive Neuroscience and Neuropathology. Amsterdam: Academic, 2009.

Sacks, Oliver W. Hallucinations. New York: Alfred A. Knopf, 2012.

(MLA 8th Edition)