What screams doesn't confuse me



Juebin Huang

, MD, PhD, Department of Neurology, University of Mississippi Medical Center

Last full review / revision Apr 2020 | Content last changed Apr 2020
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Delirium is a sudden, changing, and mostly reversible disorder of the mental state. It is characterized by difficulty concentrating, disorientation, inability to think clearly, and fluctuations in attention (state of consciousness).
  • Delirium can be caused by many diseases, drugs, and poison.

  • Doctors make the diagnosis based on symptoms and results of a physical exam, and use blood and urine samples and imaging tests to determine the cause.

  • Prompt treatment of the cause of the delirium usually cures it.

Delirium is an abnormal state of mind, not a disease. While there is a precise medical definition for the term, the term is often used to describe confusion in general.

While delirium and dementia both interfere with thinking, they are different.

  • Delirium mainly affects attention and dementia affects memory.

  • Delirium begins suddenly and often at a specific time. Dementia usually develops gradually, with no determinable point in time (see table comparing delirium and dementia).

Delirium is never a normal condition and often indicates a serious, newly developed disorder, especially in the elderly. People with delirium need immediate medical attention. If the cause of the delirium is quickly identified and corrected, it can usually be cured.

Because delirium is a temporary condition, it is difficult to determine how many people it affects. 15 to 50 percent of patients develop delirium during a hospital stay.

Delirium can occur at any age, but older people are more likely to be affected. People in retirement homes often develop delirium. In younger people, substance abuse or a life-threatening illness are common causes of delirium.


The development or worsening of many health disorders can lead to delirium. Anyone who is seriously ill or takes drugs or drugs that affect the brain (psychoactive substances) can become delirious.

Generally they are most common Causes of delirium are the following:

  • Renal insufficiency, liver failure and low levels of oxygen in the blood (hypoxia, as in pneumonia), especially if these conditions develop suddenly and get worse quickly

Other causes include hospitalization, surgery, drug withdrawal or withdrawal from a drug that has been taken for a long time, certain illnesses and poisoning.

In older people and those whose brains have been damaged by a stroke, dementia, Parkinson's disease or another disorder, delirium can develop even with less serious illnesses. Less serious illnesses that can cause delirium include:

  • Mild medical conditions (such as a urinary tract infection)

  • Using a urinary catheter (a thin tube used to empty urine from the bladder)

  • Prolonged sleep deprivation

  • Lack of sensual sensations (including social isolation and lack of visual or hearing aids)

In some people, no cause can be determined.


Being in an unfamiliar environment, such as a hospital, and especially an intensive care unit (ICU), can contribute to or trigger delirium.

In intensive care units, people are isolated in rooms that normally don't have windows or clocks. As a result, people experience a lack of sensory perception and may become disoriented. Sleep is disrupted by staff waking patients at night to observe and treat them, as well as beeping loud monitors, intercoms, corridor voices, and alarms. In addition, most people in intensive care units have serious medical conditions and are treated with drugs that make delirium more likely.

People in intensive care units may have seizures that do not cause convulsions (nonconvulsive seizures). These seizures can lead to delirium, and the seizures may not be detected because they do not cause convulsions or other typical symptoms of seizures. If the seizures go unnoticed, they may not be treated properly and in a timely manner.


Delirium is also very common after an operation, probably because of the stress of the operation, the anesthetics (anesthetics), and the pain relievers (analgesics) that are used during or after the operation.

Delirium can also develop when patients about to have surgery are not given a substance they normally take, such as recreational drugs, alcohol, or tobacco. If you stop taking such a substance, people may experience withdrawal symptoms, such as delirium.

Drug and drug use

The most common reversible cause of delirium is drugs or drugs. In younger people, illicit drug abuse and acute alcohol intoxication are common causes. In the elderly, prescription drugs are usually the cause.

Psychoactive substances act directly on the nerve cells in the brain and sometimes cause delirium. This includes the following:

Many other medicines can also cause delirium. Some examples:

  • Medicines to lower blood pressure (antihypertensive drugs, including beta blockers)

  • Digoxin and certain other medicines used to treat heart disease

drug withdrawal

Delirium can also result from suddenly stopping a drug after taking it for a long time - for example, a sedative (such as benzodiazepines or barbiturates) or an opioid pain reliever.

Alcoholics who stop drinking abruptly (delirium tremens) and heroin users who suddenly stop drinking are also often delirious.


Unusual levels of electrolytes, such as calcium, sodium, or magnesium, can disrupt the metabolism of nerve cells and lead to delirium. Such unusual electrolyte levels are caused e.g. B. by dehydration, dehydration and disorders such as kidney failure or extensive cancer.