Delirium – Causes, Signs and Symptoms



Delirium is a sudden change in mental status characterized by confusion. Patients find it difficult to pay attention or to think clearly. Between 10 and 30 percent of patients hospitalized with a medical illness experience delirium, according the American Academy of Family Physicians. Delirium may be related to many conditions, but it is always a medical emergency. Elderly people are most vulnerable to delirium.

Changes in both cognition (the mental faculty of knowing) and consciousness (an alert cognitive state) are characteristic of delirium, which tends to develop rapidly. Symptoms include disorientation, difficulty speaking and problems with memory that wax and wane over the course of the day. Symptoms typically worsen during the evening.

The chief causes of delirium are reactions to drugs (including alcohol) or withdrawal from them, in addition to physical and mental illnesses.  Delirium is usually highly reversible – in most cases, it will gradually disappear once the underlying disorder that triggered it is effectively treated or the medication that caused it has been discontinued. However, left untreated, delirium can progress to coma or even death.

Several tests can help diagnose delirium. These include a neurological examination and testing of cognitive function, motor function and levels of sensation. Blood tests, urinalysis and imaging tests may also be performed. Treatment of delirium focuses on relieving the underlying condition that is causing the delirium. The method of therapy will differ depending on the disease or disorder to be treated. Although delirium cannot always be prevented, the risk of developing the condition can sometimes be lowered by taking precautionary steps, such as engaging in normal daily tasks and getting plenty of rest.

About delirium

Delirium is a condition in which a patient becomes acutely confused because of rapid changes in how the brain functions. Between 10 and 30 percent of patients hospitalized with a medical illness experience delirium, according the American Academy of Family Physicians.

Delirium is most common in elderly people, and may result from many physical and mental illnesses. Among younger patients, delirium is more commonly related to a reaction to or withdrawal from alcohol and/or drugs. Delirium is always a medical emergency.

Delirium occurs rapidly, with changes appearing within hours or days. Patients may be confused, unable to concentrate or have difficulty understanding questions. They may be disoriented and not know where they are. They may also have problems with short-term memory. Delirium may last for about one week before it begins to subside. Although it can take weeks before cognitive levels are restored, most patients make a full recovery from delirium.

There are three major subtypes commonly associated with delirium:

  • Hyperactive delirium. Patients appear agitated, disoriented and delusional. They may also experience hallucinations. Hyperactive delirium is sometimes confused with schizophrenia or a psychotic disorder. This type of agitated delirium is most often associated with use of alcohol and/or drugs, or withdrawal from these substances. Delirium tremens (DTs) is a symptom associated with rapid withdrawal from alcohol.
  • Hypoactive delirium. Patients appear subdued, quietly confused, disoriented or apathetic. Hypoactive delirium differs from other mental conditions such as dementia or depression. However, patients with these conditions may also become delirious.
  • Mixed delirium. Patients with mixed delirium experience symptoms that fluctuate between the other two subtypes of delirium.

Delirium can be frightening for the patient and loved ones. Left untreated, delirium can progress to coma or even death. However, in most cases, delirium can be relatively easy to treat and reverse. After the patient’s underlying disease is treated, the delirium also ceases to be a problem. Prompt diagnosis and treatment is key to a favorable outcome in patients who have delirium.

Patients at greatest risk for not fully recovering from delirium are elderly people and those with compromised immune systems (e.g., HIV patients). Delirium may be confused with dementia, another cognitive disorder frequently seen among elderly people. This occurs most often in individuals with Alzheimer’s disease or who have recently experienced a stroke. Dementia is a condition in which cognitive functions, especially orientation and memory, worsen gradually. Delirium occurs suddenly and may involve only levels of attention or confusion. However, people with dementia may also become delirious. For these patients, information from family members or caregivers is especially important during treatment to distinguish the patients’ changes from their original mental status.

Risk factors and causes of delirium

Many different conditions can cause delirium, especially those that cause a lack of oxygen to the brain. Conditions such as acute meningitis or encephalitis (inflammations of the central nervous system) are also associated with delirium.

Diseases in other areas of the body can also cause delirium. For example, infections such as urinary tract infections or pneumonia can cause delirium in people who have had prior brain damage due to conditions such as strokes or dementia. About 25 percent of patients hospitalized with cancer and 30 to 40 percent of patients hospitalized with HIV infection also experience delirium, according to the American Academy of Family Physicians (AAFP).  

Use of drugs including alcohol can also cause delirium, especially in elderly people. Even over-the-counter or prescription medications such as antihistamines (which relieve symptoms of colds and allergies) can cause delirium in some people.

Other conditions associated with delirium include:

  • Withdrawal from certain types of legal and illegal drugs
  • Medical conditions such as malnourishment, thyroid disease, heart disease and liver disease
  • Dehydration
  • Imbalances of fluids and electrolytes, or acids and bases
  • Seizures
  • Burns
  • Poisons in the body (e.g., arsenic)
  • Recovery from surgery

Elderly patients are at an increased risk for delirium, especially when they are hospitalized or live in nursing homes. Up to 60 percent of nursing home residents older than age 75 experience delirium, according to the AAFP. Other people at greater risk for developing delirium include people with multiple medical conditions or who take multiple medications.

Signs and symptoms of delirium

Rapid shifting of mental states is the major characteristic of delirium. For example, patients may go from feelings of lethargy to sudden agitation before quickly shifting back into lethargy. In hospitalized patients, agitation during delirium may include attempting to pull out intravenous (I.V.) lines or catheters.

Symptoms associated with delirium may come and go throughout the course of the day, but typically worsen at night. Delirium during evening hours is sometimes referred to as “sundowning.” It is especially common among elderly patients who are hospitalized or in nursing homes. The phenomenon is not well understood, but may be related to disorientation regarding a normal day/night schedule.

Patients with delirium may lack the ability to focus or concentrate on ideas or tasks. They may become confused easily and have trouble paying attention or following instructions. They may also find it difficult to engage in purposeful thinking or behavior. Memory deficits are common.  

Delirium is also marked by a lack of organization in thinking, which is revealed by a patient’s unintelligible speech and an inability to alter speech patterns or behavior. Disorientation often leaves patients unaware of time and place, a symptom potentially made worse by changes in sensation and perception that trigger hallucinations. People who are delirious usually experience visual hallucinations. People with mental disorders such as schizophrenia and bipolar disorder may also experience hallucinations, but more commonly those hallucinations are auditory.

Additional neurologic symptoms are also commonly observed in patients with delirium. These include unsteady gait, tremor and twitching, and difficulty reading and writing.

Other symptoms include:

  • Altered consciousness or awareness
  • Drowsiness or changed sleep patterns
  • Alertness levels that shift (usually higher in the morning, lower at night)
  • Impairment of short-term memory and recall
  • Impairment of motor abilities
  • Body movements – such as increased restlessness – brought on by changes in the central nervous system
  • Changes of emotion or personality, such as increased anxiety, anger, depression, euphoria or irritability
  • Apathy and withdrawal

Diagnosis methods for delirium

Sudden confusion is almost always a sign of delirium, and anybody who experiences this symptom should see a physician. Delirium is a medical emergency, and in many cases patients who experience signs of delirium will be immediately hospitalized so a physician can observe and diagnose their condition.

The physician will perform a complete physical examination and compile a thorough medical history. A neurological examination should be performed to check for abnormalities that are indicators of delirium. Testing may include studies of the patient’s psychological makeup, cognitive function, motor function and levels of sensation. Common tests may include a mental status examination, which checks such things as whether the patients know where they are and the date and time.

Imaging tests such as computed axial tomography (CAT) scans and magnetic resonance imaging (MRI) may help a physician to detect brain abnormalities responsible for delirium. Blood testing may also be performed to measure levels of electrolytes, calcium, magnesium, glucose and creatine phosphokinase.

Other tests that may be performed include:

  • Liver function tests

  • Thyroid function tests

  • Electroencephalogram (EEG, records activity of brain waves)

  • CSF (cerebrospinal fluid) analysis that examines fluid near the brain and spinal cord

  • Chest x-ray

  • Urinalysis

  • Urine or blood tests to determine the presence of drugs

Certain mental health disorders share many of the characteristics of delirium. However, certain symptoms (e.g., visual hallucinations) are more likely to occur with delirium than with other mental health disorders, such as schizophrenia and bipolar disorder. For patients with dementia who also experience delirium, it is important for the physician to find out their previous mental status from family members or caregivers to determine the extent of deterioration.

Delirium is diagnosed if:

  • The patient exhibits reduced clarity of awareness regarding the surrounding environment, coupled with reduction in the ability to focus, sustain or shift attention.

  • The patient has changes in cognition such as memory problems, disorientation or disturbances in language. These changes cannot be better accounted for by dementia.

  • The disturbance develops over a short period of time, usually hours or days. Symptoms fluctuate during the course of the day.

In addition, the specific type of delirium that is diagnosed will vary according to medical history, physical examination or laboratory findings that point to the following:

Delirium due toFindings
General medical conditionThe disturbance is caused by physiological consequences of a general medical condition.
Substance intoxicationThe symptoms related to the first two criteria developed during substance intoxication; or medication caused the delirium.
Substance withdrawalThe symptoms related to first two criteria developed during, or shortly after, the substance withdrawal. 

Treatment options for delirium

Treatment of delirium is focused on relieving the underlying condition that is causing the delirium. The method of therapy will differ depending on the disease or disorder to be treated.

In some cases, delirium can be reduced by stopping or reducing the use of certain medications known to increase confusion. These include:

  • Anticholinergics
  • Analgesics (pain relievers)
  • Cimetidine (used to treat gastrointestinal disorders)
  • Central nervous system (CNS) depressants
  • Lidocaine (an anesthetic)
  • Alcohol and illegal drugs
  • Antihistamines

Certain medical conditions may also cause added confusion in patients who have delirium. Treating the following conditions can ease such feelings of confusion:

  • Heart failure
  • Decreased oxygen (hypoxia)
  • Excessive carbon dioxide levels (hypercapnia)
  • Thyroid disorders
  • Anemia (abnormally low levels of red blood cells)
  • Nutritional disorders
  • Infections
  • Kidney failure
  • Liver failure
  • Psychiatric conditions such as depression

Some patients who experience delirium may engage in aggressive or violent behavior that can be treated with medications such as the vitamin thiamine, sedatives and dopamine blockers. Antipsychotic drugs can be used to relieve agitation associated with delirium. Anti-anxiety medications that are normally used to relieve agitation  (e.g., benzodiazepines) can actually increase confusion among delirious patients and should not be used. In some cases, these patients will require hospitalization, monitoring and possibly restraints to prevent them from hurting themselves or others. When the underlying condition is treated promptly, delirium typically fades over time and the patient makes a full recovery. Delay in treatment greatly raises the risk that recovery will not be complete.

Prevention methods for delirium

Delerium cannot typically be prevented. However, in rare instances, the risk of developing the condition can be reduced by taking precautionary steps. This is especially true of older patients, who are at much higher risk of delirium than patients in other age groups.

Prevention tips include:

  • Keep physically and mentally active. Patients should not remain in bed all the time, but should instead take time to walk around. Patients should also remain mentally active by reading, engaging others in conversation or keeping interested in hobbies.
  • Use tools to remain properly oriented. Patients should wear their glasses and hearing aids to help keep them fully engaged with their surroundings. Placing clocks and calendars nearby can also help with orientation. Using lights or opening curtains to maintain a patient’s day/night orientation in hospitals or nursing homes can also help.
  • Complete normal daily tasks to the greatest extent possible. Even basic tasks such as dressing oneself can help keep patients oriented and alert.
  • Get plenty of sleep. Patients should make efforts to remain fully rested by sleeping in places that are quiet and free of interruptions.
  • Consume proper amounts of foods and fluids.

Questions for your doctor regarding delirium

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Friends and family members of patients may wish to ask the doctor the following delirium-related questions:

  1. Why do you suspect that my loved one has delirium?
  2. What symptoms should I watch for that might indicate delirium?
  3. Is it possible that another condition is causing my loved one’s symptoms?
  4. Which tests will you use to diagnose my loved one’s delirium?
  5. What type of delirium does my loved one have?
  6. What is the likely source of my loved one’s delirium?
  7. What are the treatment options for my loved one’s delirium?
  8. Are there ways to prevent delirium?
  9. How can I help my loved one cope with delirium?
  10. How likely is a full recovery for my loved one?
  11. What should I do if the delirium returns?
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