Delirium Fast Facts

Delirium is a state of mental confusion and disorientation. It often comes on suddenly and is temporary.

Delirium is usually a sign of an underlying medical condition.

Symptoms of delirium resemble dementia, but the two conditions are different.

Delirium is more common in older people, but it can affect anyone.

United Brain Association

Delirium is more common in older people, but it can affect anyone.

What is Delirium?

Delirium is a change in a person’s mental state that involves confusion, disorientation, or other problems with thought processes and awareness. It usually begins suddenly and may come and go.

Delirium is typically a symptom of an underlying medical condition. It is most common in older people and those hospitalized with a serious illness. 

Cognitive and mental symptoms of delirium include:

  • Trouble focusing mentally
  • Lack of responsiveness to questions
  • Distractibility
  • Problems with short-term memory
  • Disorientation
  • Rambling or incoherent speech
  • Trouble understanding speech
  • Trouble reading or writing
  • Anxiety
  • Depression
  • Angry outbursts
  • Apathy or a flat emotional state
  • Moodiness
  • Personality changes
  • Restlessness or agitation
  • Hallucinations
  • Being withdrawn
  • Lethargy
  • Sleep problems
  • Incontinence

Types of Delirium

Delirium is categorized into different types depending on its primary symptoms.

  • Hypoactive delirium is characterized by general lethargy, sleepiness, fatigue, or depression.
  • Hyperactive delirium is characterized by restlessness or agitation.
  • Mixed delirium involves shifts between the other two types.

Difference from Dementia

Delirium and dementia often look outwardly similar, but the conditions are distinct from one another. Some differences between delirium and dementia include:

  • Delirium usually comes on suddenly, while dementia develops gradually over a long time.
  • People with delirium have problems with attention and alertness. On the other hand, people with dementia, at least in its early stages, are usually alert.
  • Dementia symptoms are usually more stable than those of delirium. Delirium often comes and goes, sometimes several times a day.

Although the conditions are different, a person can have both dementia and delirium.

What Causes Delirium?

Many different illnesses, medical conditions, or situations can cause delirium. Common causes of delirium include:

  • Withdrawal from alcohol or drug addiction
  • Dehydration
  • Imbalance of certain vital chemicals such as sodium or calcium
  • Infections such as flu, COVID, pneumonia, or urinary tract infections
  • Side effects of medications such as sedatives or opioids
  • Hospitalization (especially in intensive care)
  • Poisoning (e.g., carbon monoxide)
  • Organ failure, such as kidney or liver failure
  • Severe pain
  • Stroke
  • Heart attack
  • Surgery or anesthesia
  • Sleep deprivation
  • Serious or terminal illness

Risk Factors

Delirium is more common in people with certain risk factors, including:

  • Dementia
  • Parkinson’s disease
  • Stroke
  • Liver disease
  • History of delirium
  • Multiple medical problems
  • Vision or hearing impairments

Is Delirium Hereditary?

Delirium usually results from an identifiable underlying condition and is not inherited. However, some of the conditions that can cause delirium have a genetic component; genetics may play some role in increased delirium risk. In addition, some studies have suggested that genetic factors may increase the risk of more severe delirium in older patients.

How Is Delirium Detected?

Delirium usually develops quickly, often in a matter of hours, so identifying it in its early stages can be challenging. Common early signs include:

  • Sleepiness
  • Distractibility
  • Having trouble understanding what others are saying
  • Forgetting simple details like the date or where they are
  • Agitation or restlessness
  • Hallucinations

How Is Delirium Diagnosed?

To diagnose delirium, a doctor will look for signs of impairment in attention, orientation, and memory. Exams and tests will determine the severity of the impairment and rule out other potential causes for the symptoms.

Initial diagnostic steps may include:

  • Taking a medical history
  • A physical exam
  • Neurological exams
  • Tests of mental state
  • Blood and/or urine laboratory tests

Other diagnostic steps may include:

  • More extensive cognitive exams
  • Consultation with a neuropsychologist or neurologist
  • Imaging exams to look for signs of neurological problems in the brain
  • Interviews with family members or friends


How Is Delirium Treated?

The first step in treating delirium is to focus on the underlying cause, and the proper course of treatment will vary depending on what’s causing the delirium. Common treatment options include:

  • Antibiotics if there is an underlying infection
  • Administration of fluids and electrolytes if the cause is dehydration or a chemical imbalance
  • Benzodiazepine sedatives if the cause is alcohol or drug withdrawal

To treat the symptoms of delirium itself, doctors may prescribe antipsychotic medications such as haloperidol, risperidone, olanzapine, or quetiapine.

How Does Delirium Progress?

Delirium is usually temporary, but in some cases, symptoms may last for weeks or months. When the underlying condition is treatable, delirium symptoms are likely to resolve with treatment.

The overall health of the patient may influence recovery from delirium. Otherwise healthy people often fully recover their mental abilities when the underlying condition resolves. However, people with serious health problems, such as dementia, before the onset of delirium may experience permanent cognitive decline after the delirium resolves.

People with delirium in conjunction with a serious illness are also at increased risk of complications or poor recovery from the illness.

How Is Delirium Prevented?

Because delirium is more common in hospitalized patients, hospitals can take steps to reduce the factors that increase the risk of delirium. These steps include:

  • Avoiding treatment with sedatives when possible
  • Making sure rooms are well-lit
  • Encouraging a calm, quiet environment
  • Encourage the presence of family members, and have the same staff members consistently treat the patient when possible. This may make changes in the patient’s mental state easier to spot.

Following general recommendations for good cognitive health may decrease your risk of developing delirium. These recommendations include:

  • Exercise regularly.
  • Eat a healthy diet rich in fruits, leafy greens, fish, and nuts.
  • Spend time with family and friends.
  • Keep your mind active and engaged.
  • Control Type 2 diabetes.
  • Keep blood pressure and cholesterol at healthy levels.
  • Maintain healthy body weight.
  • Stop smoking.
  • Seek treatment for depression.
  • Avoid alcohol.
  • Get plenty of sleep.

Delirium Caregiver Tips

Caring for someone affected by delirium is a challenging responsibility.  Most caregivers are family members or loved ones. They are often unprepared and untrained for the extremely difficult job of keeping the sufferer safe and as comfortable. If you’re responsible for taking care of a person living with dementia, keep these tips in mind:

  • The most important thing you can do for a loved one with delirium is to show love and support
  • Keep things simple and calm.
  • Help to improve your loved one’s sleep schedule.
  • Let your loved one know that they are safe.
  • Learn as much as possible about the specific type of delirium so that you understand what you’re facing now and what you’re likely to face in the future as the disorder progresses.
  • Be as involved as possible with the sufferer’s medical care so that you can ask questions of doctors and other healthcare professionals.
  • Don’t hesitate to ask for help from other family members or friends.
  • Take time to yourself whenever possible, and don’t neglect your own emotional and physical needs.
  • Find a support group for caregivers.

Delirium Brain Science

Scientists aren’t sure precisely what brain processes trigger delirium symptoms. Researchers are pursuing several different theories that might explain the disrupted communication between brain cells in people with delirium. The leading theories include:

  • Neurotransmitter imbalances. Unusual levels of the chemicals that allow nerve cells to communicate with each other could produce delirium symptoms. In particular, some scientists think that an excess of the neurotransmitter dopamine and a deficiency of acetylcholine could be the problem.
  • Inflammation. Some studies have associated high levels of inflammation-causing chemicals produced by the immune system with increased delirium risk in hospital patients.
  • Stress. Some scientists think high levels of the stress hormone cortisol are sometimes associated with delirium.
  • Oxygen deprivation. Other scientists believe that situations that cause decreased oxygen to the brain are to blame.
  • Sleep-wake cycle disruption. The sleep-promoting hormone melatonin could underlie some cases of delirium.

Delirium Research

Title: The Effect of Guanfacine on Delirium in Critically Ill Patients

Stage: Recruiting

Principal investigator: Andrew Barker, MD

University of Alabama at Birmingham

Birmingham, AL

Delirium in patients in the intensive care unit (ICU) is a common problem associated with increased mortality and morbidity, including increased hospital and ICU length of stay, greater hospital cost, increased ventilator days, and long-term cognitive disability. Various pharmacologic agents, including dopamine antagonists, acetylcholinesterase inhibitors, melatonin, antipsychotics, alpha-2 agonists, and glutamate antagonists, are used to treat delirium in the ICU despite the lack of clear evidence of efficacy. Since there is no evidence-based pharmacologic treatment for ICU delirium, current therapy is focused on non-pharmacologic prevention techniques, and pharmacologic agents are used once delirium is established. Guanfacine, an alpha-2 agonist, has been identified as a potential medication that may benefit the treatment of delirium. This study aims to investigate the effects of guanfacine versus placebo on delirium in critically ill patients admitted to the ICU and to determine whether guanfacine, along with standard of care, reduces the duration of delirium compared to standard of care alone.


Title: Postoperative Delirium: EEG Markers of Sleep and Wakefulness

Stage: Recruiting

Principal investigator: Ben Palanca, MD, PhD

Washington University School of Medicine

St. Louis, MO

Postoperative delirium is a condition that can develop in some older patients after they have surgery and receive general anesthesia. Patients that develop delirium have difficulty maintaining attention and thinking clearly. Both of these issues can come and go throughout the day. The incidence of postoperative delirium is greater than 25% and is associated with longer hospitalization and increased risk of persistent mental and physical decline. It is thought that this disorder may be preventable, but there is no agreed-upon way of identifying which patients are at risk for delirium before their surgery. Additionally, patients with atypical delirium are often misdiagnosed or undiagnosed postoperatively.

Based on previous research, the researchers have hypothesized that delirium may be directly related to wakefulness and sleep problems, as shown by electroencephalography [EEG]. EEG is a test that records the electrical activity of the brain through the placement of small wires on a person’s scalp. In light of this, this study aims to evaluate sleep and wakefulness using EEG before, during, and after surgery to discover any sleep or wakefulness abnormalities associated with postoperative delirium onset, severity, and length of recovery. Subjects in this study will have preoperative at-home sleep testing performed using a device called the Sleep Profiler, and questionnaires administered to characterize their mental function and brain function before surgery. When they arrive for their scheduled surgery, the subjects will be fitted with the Sleep Profiler to record brain activity during surgery and after surgery for 5 days. Postoperatively, the subjects will be asked to do simple tasks like moving toes and fingers and answer questions assessing their mental state.


Title: The Caffeine, Postoperative Delirium, and Change in Outcomes After Surgery (CAPACHINOS-2) Study

Stage: Not Yet Recruiting

Principal investigator: Phillip Vlisides, MD

University of Michigan

Ann Arbor, MI

Delirium is a syndrome characterized by failure of basic cognitive functions that affects approximately 20-50% of older surgical patients. Delirium during surgical recovery is associated with increased mortality, cognitive and functional decline, and prolonged hospitalization. In fact, 3-year survival rates for acutely hospitalized patients with delirium, and subsyndromal delirium, are both less than 50%. Older age is predictive of delirium after surgery, and with aging surgical populations, the incidence of postoperative delirium and related complications is likely to increase in the coming years.

Caffeine represents a novel, neurobiologically informed candidate intervention for reducing the risk of early postoperative delirium. Caffeine promotes arousal via adenosine receptor antagonism and improves cognitive function concurrent with increased cortical cholinergic tone. Our preliminary data suggest that caffeine reduces the risk of postanesthesia care unit (PACU) delirium in adult non-cardiac surgery patients by optimizing cortical dynamics for cognition. Furthermore, caffeine optimizes key neurocognitive processes that support information processing and may improve other related aspects of clinical recovery, such as rebound headaches in habitual caffeine users. The objective of this trial is to thus test the effects of caffeine on neurocognitive and clinical recovery after major surgery. Specifically, the primary hypothesis is that caffeine will reduce the incidence of postoperative delirium. The secondary objectives are to (1) test whether caffeine positively impacts the quality of postoperative recovery via validated patient-reported measures and (2) identify neural correlates of delirium and Mild Cognitive Impairment via advanced electroencephalographic (EEG) analysis.

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