Delirium

This article provides a comprehensive overview of delirium, including the main symptoms, specific types, causes, how it’s diagnosed, and treatment and recovery guidelines.

Key Takeaways:

• Delirium causes disturbances in attention, awareness, and cognitive functioning. It develops relatively rapidly, usually within hours to days.
• Delirium has an underlying cause. However, there are hundreds of possible causes, which makes thorough evaluation and testing essential.
• Once the underlying cause is treated, delirium often resolves. Ongoing management strategies are also essential to prevent or reduce the likelihood of future occurrences.

Understanding Delirium

Delirium is classified as a neurocognitive disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). It is characterized by disruptions in attention, awareness, and important aspects of cognitive functioning, such as memory and perception. ^[1]

Delirium usually occurs in the elderly, and often develops suddenly. Symptoms can vary from person to person, and often fluctuate in severity and frequency throughout the course of the day. ^{[1] [2]}

It is caused by an underlying medical condition, but these underlying causes can vary widely from person to person. And when combined with variation in symptoms, this makes delirium a rather complex and unique disorder. ^{[1] [2]}

Symptoms of Delirium

There are many possible symptoms of delirium. These symptoms vary from person to person, but also within each individual throughout the course of the day. Symptoms can also be acute or persistent over a longer period of time.

The main symptoms of delirium are: ^{[1] [2] [3] [4]}

• Reduced attention and awareness
• Difficulty focusing
• Trouble learning new information
• Changing subjects frequently while talking
• Disorientation (in place or time)
• Impaired perception
• Memory deficits

Individuals with delirium can also experience hyperactive, hypoactive, or mixed symptoms. Hyperactive symptoms include rapid and intense mood swings, and agitation, while hypoactive symptoms include lethargy, sluggishness, and incoherent speech. Some people have mixed symptoms, where they alternate between periods of each. ^{[1] [3] [4]}

Some individuals with delirium also experience psychotic symptoms, such as delusions or hallucinations. This is more common in hyperactive cases. ^{[1] [3]}

Types of Delirium

There are several types of delirium. Firstly, there are three subtypes of delirium based on specific symptoms, which include: ^{[1] [4]}

• Hyperactive delirium: Characterized by hyperactive motor activity, and involves agitation, rapid mood swings, and/or refusal to cooperate with medical care.
• Hypoactive delirium: Characterized by hypoactive psychomotor activity, and involves sluggishness and lethargy, approaching insensibility or near unconsciousness.
• Mixed delirium: This includes individuals who experience alternations between hyperactive and hypoactive states.

There are also specific types of delirium based on the causes. This includes: ^[1]

• Substance intoxication delirium
• Substance withdrawal delirium
• Medication-induced delirium
• Delirium due to another medical condition

Substance Intoxication Delirium

Delirium can be caused by many substances, including alcohol, cannabis, sedatives, anxiolytics, and opioids. This is diagnosed when substance intoxication causes severe enough symptoms of disturbed attention, awareness, and cognitive functioning.

Substance Withdrawal Delirium

Withdrawal from alcohol, opioids, sedatives, hypnotics, and anxiolytics can also cause delirium. This is diagnosed when the delirium symptoms are severe enough to require clinical attention.

One example of this is delirium tremens, also known as alcohol withdrawal delirium. It involves shaking, confusion, hallucinations, and other symptoms. It can be life-threatening.

Medication-Induced Delirium

Sometimes, delirium can occur after taking prescribed medicines, such as opioids, sedatives, or cannabis receptor agonists. Medication side effects account for up to 39% of delirium cases. ^[1]

Delirium Due to Another Medical Condition

Delirium can also occur due to various medical conditions, such as:

• Infections
• Acute illness
• Metabolic disorders

Delirium and Dementia

Delirium and dementia can be difficult to distinguish due to their overlapping symptoms. Furthermore, there are other factors that make it more complex, such as:

• Delirium and dementia can sometimes occur simultaneously
• Dementia can develop later on after an episode of delirium

However, the key difference between delirium and dementia is that delirium has a rather rapid onset and is usually temporary, whereas the symptoms of dementia are much more gradual and long-lasting. As a result, delirium often gets resolved once the underlying cause is addressed, whereas dementia is a progressive condition.

Causes

Delirium, by its official definition, has an underlying cause. However, these causes can vary greatly from person to person. Research has identified over 100 possible causes (also referred to as precipitating factors), which can generally be grouped into the following categories: ^[5]

• Surgery/Surgical Factors
• Systemic illness or organ dysfunction
• e.g. neurological injury, infection, pain, kidney injury, hypoxemia
• Metabolic abnormalities
• e.g electrolyte imbalance, low albumin
• Pharmacology (i.e. medication/ substance use)
• e.g. benzodiazepines, opioids, sedatives
• Iatrogenic and environmental factors
• e.g physical restraint, ICU admission, longer hospital stay
• Trauma
• Biomarker Levels
• e.g. elevated CRP and IL-6
• Neurotransmitter Levels
• e.g. high tryptophan

In general, the reason these factors can cause delirium is their impact on neurological functioning. These factors can cause stress, inflammation, neurotransmitter imbalance, poor blood flow and oxygenation, reduced brain energy metabolism, and other consequences that ultimately cause brain degeneration and cognitive dysfunction. ^{[1] [2] [3] [6]}

These factors don’t always cause delirium, but rather can lead to its development, especially when combined with the risk factors described below.

Risk Factors

There are many identified risk factors of delirium, including: ^{[1] [4]}

• Older age
• Cognitive impairment or dementia
• Cardiovascular disease
• Male sex
• Alcohol use
• Depression
• Malnutrition
• Sleep deprivation
• Poor vision or hearing

If someone has one or more of these risk factors, they are more vulnerable to developing delirium, and are thus more likely to be affected by the precipitating factors mentioned above.

How Common is It?

The overall prevalence of delirium is 1 to 2%. This increases to over 14% in individuals ages 85 and older. ^[3]

Prevalence rates are significantly higher in hospitalized individuals. It affects anywhere from 10 to 50% of hospitalized older patients, 14 to 24% of individuals in the emergency department, 15 to 53% of post-operative patients, and as high as 87% of intensive care unit (ICU) patients. ^{[1] [3] [6]}

Diagnosing Delirium

Diagnosing delirium is a multi-step process, including a thorough history, comprehensive physical exam, lab testing, and imaging in certain cases. All of these steps are necessary to rule out other causes and ensure an accurate diagnosis.

Seeking early evaluation is very important to determine the underlying cause and start treatment, especially since some causes of delirium can be life-threatening.

Initially, the doctor will conduct an assessment of the individual’s attention, arousal, and overall cognitive and mental status. They will then interview caregivers or medical staff who know the patient, to see if there have been any acute changes in attention or arousal.

Tests and Assessments

Many tests and assessments are used to diagnose delirium. The first assessment used is a comprehensive physical exam, which may include the following tests: ^{[1] [2] [4]}

• Complete blood count
• Complete metabolic panel
• Arterial blood analysis
• Urinalysis
• Bladder scan

More advanced testing that may be used in some cases include: ^{[1] [2] [4]}

• Chest x-ray
• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Lumbar puncture (spinal tap)
• Electroencephalogram (EEG)
• Toxicology screening

All of these tests have a common goal of identifying the underlying causes of delirium. Since there are many possible causes, this is why several tests are often needed.

Beyond this, diagnosis involves specific validated measures for delirium and related symptoms. Common assessments to specifically assess delirium include: ^{[1] [2]}

• Confusion Assessment Method (CAM): This is the most commonly used tool. It is designed to assess change in mental status, inattention, disorganized thinking, and altered level of consciousness.
• There are also variations depending on the context, such as a briefer version and one for ICU patients
• 4 A’s Test (4AT): This test measures alertness, attention, acute change in mental status, and orientation to time and place.
• Delirium Observation Screening Scale: This scale is designed to be used by nurses to measure changes in the patient’s communication, mood, and other behaviors associated with delirium.

After these assessments. the symptoms are compared to the following criteria in the DSM-5: ^[1]

• Disturbance in attention and reduced awareness
• Disturbance develops over a short period of time, represents a significant change from baseline function, and fluctuates in severity during the day
• At least one other disturbance in cognition
• Disturbances are not better explained by a neurocognitive disorder or a severely reduced level of arousal
• Evidence of a direct cause or causes

Treatment and Recovery

Treatment for delirium is centered around addressing the underlying cause. Early treatment is vital, especially since many causes of delirium can be severe or life-threatening. Fortunately, delirium is most often short-lived and resolves once the underlying issues are treated. ^[1]

Also, an essential part of treatment is prevention. This is important since many individuals who experience delirium once may also experience it again, especially if risk factors are not addressed. Therefore, a variety of prevention strategies are used to help lower the risk, such as: ^{[1] [2] [4] [6]}

• Daily screening for delirium
• Avoidance of side effect-prone medications
• e.g. benzodiazepines, antipsychotics
• Adequate hydration and nutrition
• May include specific nutritional or hydration therapies
• Decrease environmental disturbances
• Promote uninterrupted sleep
• May include an eye mask, ear plugs, etc.
• Early identification of infection
• Effective treatment of pain
• Daily movement
• Avoidance of physical restraints
• Minimizing catheter use
• Treating metabolic disorders
• Addressing cardiorespiratory dysfunction

Medications are considered a last resort treatment for delirium. However, they may be beneficial in some cases, such as the following examples: ^{[1] [2]}

• Benzodiazepines for individuals with alcohol withdrawal syndrome
• Antipsychotics for severe cases of hyperactive delirium

Home Management and Additional Support

The above treatments are often first administered in hospital settings. However, many patients end up out of the hospital and back at home, so it’s important to be aware of home management and other supportive strategies.

If you’re caring for someone with a history of delirium, the following home management tips can provide them with support and promote better functioning: ^{[1] [4] [7]}

• Maintain regular sleep/wake cycles
• Implement daily routines
• Use clocks, calendars, and other tools
• Ensure regular meals and adequate fluid intake
• Include family members in at-home care
• Encourage regular activity and movement
• Keep familiar and favorite objects in the house
• Reduce noise, clutter, and other distractions
• Make sure they use eyeglasses and hearing aids (if needed)
• Use clear, calm communication
• Avoid arguing, confrontation

Author

Jack Cincotta

Jack Cincotta holds a M.S. degree in Psychology. He is also a board-certified holistic health practitioner through AADP and an AFPA-certified holistic health coach and nutritionist.

Activity History - Last updated: March 19, 2026, Published date: March 19, 2026

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Reviewer

Jennifer Brown

Dr. Jennifer Brown is dual board-certified in family medicine and obesity medicine. She currently works for Amwell Medical Group, providing virtual primary care services, including mental health treatment.

Activity History - Medically reviewed on April 2, 2026 and last checked on March 19, 2026