Definition of Delirium:

Delirium is sudden severe confusion and rapid changes in brain function that occur with physical or mental illness.

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.

Causes include:

• Drug abuse
• Infections such as urinary tract infections or pneumonia (in people who already have brain damage from stroke or dementia)
• Poisons
• Fluid/electrolyte or acid/base disturbances

Patients with more severe brain injuries are more likely to get delirium from another illness.