Table of Contents

Definition of Delirium

Delirium refers to a state of acute confusion and rapid changes in brain function that can cause disturbances in awareness, attention, thinking, memory, perception, and behavior. It is typically a temporary condition and often occurs suddenly. Delirium can manifest as disorientation, incoherent speech, hallucinations, agitation, reduced consciousness, and difficulty concentrating.

This condition can be caused by various factors such as underlying medical conditions, infections, drug reactions, dehydration, alcohol or drug withdrawal, or changes in metabolic balance. Delirium is commonly observed in hospitalized patients, particularly older adults, but it can affect individuals of any age.

Prompt identification and treatment of the underlying cause are crucial for managing delirium and preventing complications. Healthcare professionals typically focus on addressing the root cause while providing supportive care to manage symptoms and help the individual return to a more coherent and functional state.


History of Delirium

The understanding and recognition of delirium as a medical condition have evolved over centuries. The term “delirium” itself originates from the Latin word “delirare,” meaning “to go off the furrow” or “to deviate from the plowed track,” emphasizing the departure from a normal state of mind.

  • Historically, descriptions of delirium-like states can be traced back to ancient civilizations. In ancient Greek and Roman times, physicians documented symptoms resembling delirium and associated them with various causes, including fever, infection, head injuries, and substance intoxication.
  • During the Middle Ages and the Renaissance, delirium was often attributed to supernatural or mystical causes. It was commonly viewed as possession by evil spirits or a punishment from the divine rather than being recognized as a medical condition.
  • Advancements in medicine during the 19th and 20th centuries led to a more systematic approach to understanding delirium. The work of clinicians and researchers helped differentiate delirium from other mental health conditions. The development of standardized diagnostic criteria and classifications improved the identification and management of delirium.
  • In modern times, medical science has furthered our understanding of the underlying causes and risk factors associated with delirium. There’s a greater appreciation for its prevalence among certain populations, such as older adults in hospitals or those with specific medical conditions. Moreover, research continues to explore the neurobiological mechanisms contributing to delirium and effective strategies for its prevention and treatment.

Overall, the history of delirium reflects a progression from mystical explanations to a more nuanced understanding within the context of medical science, leading to improved recognition, diagnosis, and management of this complex condition.

DSM-5 Criteria of Delirium

In the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition), delirium is classified as a neurocognitive disorder. The DSM-5 provides specific criteria for diagnosing delirium, emphasizing the acute onset of disturbances in attention, awareness, and cognition. To diagnose delirium, the following criteria must be met:

A. Disturbance in attention (i.e., reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment).

B. The disturbance develops over a short period (usually hours to days) and tends to fluctuate during the course of the day.

C. Additional disturbances in cognition (e.g., memory deficit, disorientation, language disturbance, perceptual disturbance) that go beyond what is typical for the individual and are not better explained by a pre-existing, established, or evolving neurocognitive disorder.

D. There is evidence from the history, physical examination, or laboratory findings that the disturbance is a direct physiological consequence of another medical condition, substance intoxication or withdrawal, or exposure to a toxin, or it may be due to multiple etiologies.

E. The disturbance is not better explained by another pre-existing, established, or evolving neurocognitive disorder and does not occur exclusively during the course of a severe major neurocognitive disorder or a terminal illness.

The DSM-5 criteria are essential for clinicians to assess and diagnose delirium accurately. These criteria help differentiate delirium from other neurocognitive disorders and guide appropriate evaluation and management to address the underlying causes or contributing factors.

Etiology of Delirium

Delirium can have multifactorial causes, and it often arises from a combination of predisposing and precipitating factors. Understanding the various etiological factors of delirium is crucial for proper diagnosis and management. Some common causes and contributors include:

Underlying Medical Conditions:

Delirium can be a result of various medical conditions such as infections (e.g., urinary tract infections, pneumonia), metabolic imbalances (e.g., electrolyte disturbances, liver or kidney failure), cardiovascular issues (e.g., heart failure, stroke), respiratory problems, or neurological disorders (e.g., seizures, head trauma).

Substance Intoxication or Withdrawal:

Use of drugs, including alcohol, certain medications, or withdrawal from substances, can precipitate delirium. This includes benzodiazepines, opioids, anticholinergic medications, and others.

Dehydration and Malnutrition:

Lack of proper hydration or nutrition can contribute to delirium, especially in older adults or individuals with chronic illnesses.

Psychiatric Conditions:

Mental health disorders, such as depression, anxiety, or schizophrenia, can sometimes lead to delirium, particularly during acute exacerbations or in the presence of other contributing factors.

Environmental Factors:

Hospitalization, especially in intensive care units, changes in surroundings, sensory deprivation or overload, sleep disturbances, and disruptions in the circadian rhythm can all contribute to the development of delirium.

Surgery or Medical Procedures:

Delirium can occur postoperatively, especially in older adults, due to the stress of surgery, anesthesia, pain medications, and changes in routine.

Trauma or Pain:

Severe pain, traumatic injury, or extensive physical stress can trigger delirium.

Advanced Age:

Older adults are more susceptible to delirium due to factors like pre-existing medical conditions, sensory impairments, polypharmacy, and changes in brain structure and function associated with aging.

Identifying and addressing these underlying factors are crucial steps in managing delirium. Sometimes, multiple factors may contribute simultaneously to the development of delirium, making its diagnosis and management complex and requiring a comprehensive evaluation by healthcare professionals. Treatment involves addressing the root causes while managing symptoms to ensure the patient’s safety and well-being.

Theories related to Delirium

Several theories attempt to explain the underlying mechanisms and pathophysiology of delirium. These theories provide insights into the complex nature of this condition and help guide research and treatment approaches. Some notable theories include:

Neurotransmitter Imbalance Theory:

Delirium is associated with alterations in neurotransmitters in the brain, particularly acetylcholine, dopamine, gamma-aminobutyric acid (GABA), serotonin, and norepinephrine. Imbalances in these neurotransmitter systems may contribute to the development of delirium. For instance, decreased acetylcholine and increased dopamine activity have been implicated in certain forms of delirium.

Inflammatory and Immune Response Theory:

Evidence suggests that inflammation and immune system activation play a role in delirium. In response to various triggers (e.g., infection, surgery), the body’s inflammatory response can impact the brain, leading to neuroinflammation and changes in brain function that contribute to delirium.

Neurocognitive Network Dysfunction Theory:

Delirium is thought to result from disruptions in neural networks and connectivity within the brain. Dysfunction in these networks, involving various brain regions responsible for attention, executive function, and memory, may underlie the cognitive disturbances observed in delirium.

Oxidative Stress and Mitochondrial Dysfunction Theory:

The imbalance between the production of reactive oxygen species (ROS) and the body’s ability to detoxify them can lead to oxidative stress. This oxidative stress, along with mitochondrial dysfunction, may contribute to neuronal damage and cognitive impairment seen in delirium.

Neurotransmitter Receptor Sensitivity Theory:

Changes in the sensitivity or responsiveness of neurotransmitter receptors, such as acetylcholine or GABA receptors, within the brain may contribute to the development of delirium. Altered receptor function could result from various triggers like medications, metabolic imbalances, or stressors.

Brain Network Disruption Theory:

Delirium is viewed as a disturbance in the complex interactions between different brain networks, including the default mode network (DMN), attentional networks, and salience networks. Disruptions in these networks can impair cognitive processing and lead to the characteristic symptoms of delirium.

These theories are not mutually exclusive and often interact in complex ways, contributing to the development and manifestation of delirium. Research continues to explore these theories to gain a deeper understanding of the underlying mechanisms, which may aid in the development of more targeted interventions and treatments for delirium.

Risk factors of Delirium

Several risk factors increase the likelihood of developing delirium. These factors can be broadly categorized into predisposing and precipitating factors. Predisposing factors are characteristics or conditions that make an individual more vulnerable to delirium, while precipitating factors are events or triggers that directly lead to its onset. Some common risk factors include:

Predisposing Factors:

  • Advanced Age: Older adults are at higher risk due to factors like cognitive decline, multiple comorbidities, sensory impairments, and altered metabolism.
  • Cognitive Impairment: Pre-existing dementia, Alzheimer’s disease, or other neurocognitive disorders increase susceptibility to delirium.
  • Medical Comorbidities: Chronic conditions such as diabetes, cardiovascular disease, respiratory disease, and renal dysfunction can predispose individuals to delirium.
  • Sensory Impairment: Vision or hearing impairment can contribute to disorientation and confusion, increasing the risk of delirium.
  • Polypharmacy: Taking multiple medications, especially those with psychoactive effects or anticholinergic properties, raises the risk of delirium.
  • Functional Dependence: Individuals with limited mobility or functional dependence are more susceptible due to increased vulnerability to stressors and changes in routine.

Precipitating Factors:

  • Infections: Urinary tract infections, respiratory infections, sepsis, and other systemic infections can trigger delirium.
  • Medication Use: Certain medications, such as benzodiazepines, opioids, anticholinergics, and psychoactive drugs, can precipitate delirium, particularly in susceptible individuals.
  • Substance Intoxication or Withdrawal: Alcohol, illicit drugs, or abrupt cessation of certain medications can induce delirium.
  • Surgery or Hospitalization: The stress of surgery, anesthesia, postoperative pain, and hospitalization, especially in intensive care settings, can trigger delirium.
  • Dehydration or Malnutrition: Inadequate fluid intake or nutrition can contribute to delirium, especially in older adults.
  • Metabolic Disturbances: Electrolyte imbalances, hepatic or renal dysfunction, or metabolic derangements can lead to delirium.
  • Psychological Stressors: Emotional stress, anxiety, or traumatic events can precipitate delirium in susceptible individuals.
  • Environmental Factors: Changes in the environment, including sensory overload or deprivation, disrupted sleep patterns, and unfamiliar surroundings, can trigger delirium.

Recognizing these risk factors and addressing modifiable ones can help in preventing or reducing the incidence of delirium. In clinical settings, identifying and managing these risk factors play a crucial role in the prevention and management of delirium, especially in vulnerable populations.


Treatment for Delirium

The treatment of delirium involves addressing its underlying causes, managing symptoms, ensuring patient safety, and providing supportive care. The approach to treating delirium is multifaceted and may include the following components:

Identifying and Managing Underlying Causes:

  • A thorough assessment to identify and address the precipitating factors contributing to delirium, such as infections, medication side effects, metabolic imbalances, or other medical conditions.
  • Adjusting or discontinuing medications that might exacerbate delirium, especially those with psychoactive effects or anticholinergic properties.

Supportive Care:

  • Creating a calm and safe environment, ensuring adequate lighting, minimizing noise, and maintaining a regular sleep-wake cycle to support the patient’s orientation and comfort.
  • Reorienting the individual by using clocks, calendars, and familiar objects to improve their sense of time and place.
  • Encouraging family or familiar faces to be present, as this can provide comfort and reassurance.

Medication Management:

  • In some cases, medications may be used to manage specific symptoms associated with delirium, such as agitation or severe distress. However, medications should be used cautiously and under close medical supervision due to the risk of worsening confusion.
  • Antipsychotic medications might be considered in specific situations when agitation or psychosis is severe and poses a risk to the individual or others. These should be used at the lowest effective dose for the shortest duration possible.

Treatment of Underlying Medical Conditions:

  • Addressing and treating any identified medical conditions contributing to delirium, such as infections, electrolyte imbalances, or organ dysfunction.

Support for Functional Recovery:

  • Rehabilitation and physical therapy to aid in recovery and regain functional abilities, especially in cases where delirium has resulted in physical deconditioning or loss of mobility.

Monitoring and Reassessment:

  • Regular monitoring of the patient’s cognitive status, vital signs, and overall condition to track improvement or any potential complications.
  • Frequent reassessment of the underlying causes and modifying treatment strategies accordingly.

It’s crucial to involve a multidisciplinary team, including physicians, nurses, pharmacists, and other healthcare professionals, in the management of delirium. Additionally, family members or caregivers play an essential role in providing support and assisting with reorientation and comfort measures.

Prevention strategies, such as early mobilization, optimizing sleep, minimizing polypharmacy, and addressing modifiable risk factors, are also vital in reducing the incidence of delirium, especially in high-risk populations like older adults or those in intensive care settings.

Therapies for Delirium

Therapeutic interventions for delirium focus on managing symptoms, supporting cognitive function, and addressing underlying causes. While there isn’t a specific therapy that universally treats delirium, several approaches and therapies can help manage and support individuals experiencing delirium:

Non-Pharmacological Interventions:

  • Reorientation Techniques: Providing consistent information about time, place, and person to help the individual regain orientation.
  • Environmental Modifications: Creating a calm, familiar, and well-lit environment to minimize confusion and agitation.
  • Promotion of Sleep Hygiene: Maintaining a regular sleep-wake cycle and reducing disruptions to promote restful sleep.
  • Family Involvement: Encouraging family members or caregivers to provide emotional support, reassurance, and familiar interactions.
  • Cognitive Stimulation: Engaging in activities that stimulate cognition, such as puzzles, conversation, or music therapy, when appropriate and tolerated.
  • Mobility and Rehabilitation: Encouraging early mobilization and physical activity to prevent deconditioning and maintain functional abilities.

Pharmacological Interventions:

While medications are generally not the first-line treatment for delirium, in certain situations where symptoms are severe and pose a risk to the individual or others, medications may be considered under close medical supervision.

  • Antipsychotic Medications: These may be used cautiously for severe agitation, hallucinations, or delusions. However, their use should be limited to specific situations due to potential side effects and increased mortality risk, especially in elderly patients.
  • Benzodiazepines: These are generally avoided or used sparingly due to the risk of worsening confusion and increasing the duration of delirium.

Multidisciplinary Care and Communication:

  • Involvement of a multidisciplinary team including physicians, nurses, psychologists, occupational therapists, and other specialists to provide comprehensive care.
  • Effective communication among healthcare providers, patients, and caregivers to ensure continuity of care and consistent management.

Nutritional Support:

  • Ensuring adequate hydration and nutrition, as dehydration and malnutrition can exacerbate delirium.

Educational and Supportive Interventions:

  • Providing education and support to caregivers, family members, and patients about delirium, its causes, and strategies for managing symptoms.

The choice of therapy and interventions for delirium should be tailored to the individual’s specific needs and medical condition. A holistic approach that combines various non-pharmacological strategies along with addressing underlying medical issues tends to be the most effective in managing and improving outcomes for individuals experiencing delirium.

Preventions of Delirium

Preventing delirium involves identifying and managing risk factors, implementing strategies to minimize its occurrence, and providing appropriate care for individuals susceptible to this condition. Here are several key preventive measures:

Comprehensive Assessment and Management of Risk Factors:

  • Identify and manage predisposing factors such as advanced age, cognitive impairment, medical comorbidities, sensory impairments, and functional dependence.
  • Address precipitating factors including infections, medication use, surgery, dehydration, and metabolic disturbances through appropriate interventions.

Medication Review and Optimization:

  • Conduct regular medication reviews to minimize polypharmacy and avoid medications that can contribute to delirium, especially those with anticholinergic effects or psychoactive properties.
  • Consider using alternative medications or adjusting doses to reduce the risk of delirium.

Environmental Modifications:

  • Create a calm, well-lit, and familiar environment, particularly in healthcare settings, to reduce sensory overload and disorientation.
  • Maintain a regular sleep-wake cycle and minimize disruptions to promote restful sleep.

Early Mobilization and Rehabilitation:

  • Encourage physical activity and rehabilitation to maintain mobility and functional abilities, especially for individuals at risk due to hospitalization or reduced mobility.

Hydration and Nutrition:

  • Ensure adequate hydration and nutrition to prevent dehydration and malnutrition, which can contribute to the development of delirium, especially in older adults.

Cognitive Stimulation and Engagement:

  • Engage individuals in activities that stimulate cognition and social interaction to maintain mental stimulation and reduce the risk of delirium.

Multidisciplinary Approach and Education:

  • Involve a multidisciplinary team in healthcare settings to provide comprehensive care and education to staff, caregivers, and patients about delirium prevention strategies.
  • Educate patients, families, and caregivers about the importance of recognizing early signs of delirium and seeking prompt medical attention.

Routine Monitoring and Assessment:

  • Conduct regular monitoring and assessment of individuals at high risk of delirium, especially during hospitalization or following significant medical events.

Preventing delirium requires a proactive and multifaceted approach that involves addressing modifiable risk factors, promoting a supportive environment, providing adequate care, and fostering collaboration among healthcare professionals, patients, and caregivers. Implementing these preventive measures can significantly reduce the incidence and severity of delirium, particularly in vulnerable populations.

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