DeliriumEdit

Delirium is an acute disturbance of attention and awareness that develops over a short period of time and tends to fluctuate in severity during the day. It is a neuropsychiatric syndrome that can occur in people of any age but is especially common and dangerous in older adults who are hospitalized or recovering from major illness or surgery. Delirium is not a single disease; it is a syndrome with many possible underlying causes, including medical, surgical, infectious, metabolic, and medication-related factors. Because delirium often signals an underlying, treatable problem, timely recognition and management are central to patient safety and outcomes. See also Delirium Tremens and Delirium in the ICU for related forms and settings.

In clinical practice, delirium is often described as a spectrum that includes hyperactive, hypoactive, and mixed presentations. Hyperactive delirium features agitation, restlessness, and clear signs of distress, whereas hypoactive delirium can present with quiet confusion, lethargy, and reduced responsiveness, which may be easily overlooked. Mixed delirium alternates between these states. The condition can complicate recovery from surgery, infections, and chronic diseases, and it is linked with longer hospital stays, higher mortality, and a greater risk of persistent cognitive impairment after discharge. See Hyperactive delirium and Hypoactive delirium for more on the different presentations.

Signs and symptoms

  • Acute onset and fluctuating course
  • Disturbance in attention (difficulty sustaining, shifting, or focusing)
  • Disorganized thinking and impaired perception or misperceptions
  • Altered level of consciousness or arousal
  • Disorientation in time and place, with possible memory deficits
  • Sleep-wake cycle disturbances and psychomotor changes
  • Potential perceptual disturbances, such as misinterpretations or hallucinations

Causes and risk factors

Delirium arises from an interplay of brain vulnerability and external stressors. Common etiologies include: - Acute medical illnesses (infection, dehydration, electrolyte imbalance) Infection; Electrolyte imbalance - Postoperative states, particularly after major surgery - Polypharmacy and anticholinergic burden (the cumulative effect of multiple medications) Polypharmacy; Anticholinergic burden - Sedatives and opioids, especially in the ICU or post-anesthesia settings; benzodiazepines are particularly implicated in certain subtypes Benzodiazepines; Opioids - Metabolic disturbances (hypoxia, liver or kidney dysfunction) - Alcohol withdrawal and other substance-related factors - Dementia or other neurodegenerative disease, with delirium superimposed on dementia (DSD) Delirium superimposed on dementia - Sensory impairment, immobility, and sleep disruption

Risk factors often cluster in older adults and medically complex patients. Important protective factors include adequate hydration and nutrition, effective pain management, early mobilization, functional orientation, proper correction of sensory deficits (glasses, hearing aids), and minimization of delirium-inducing medications.

Diagnosis

Delirium is diagnosed clinically based on history, observation, and targeted examinations to identify underlying causes. In practice, clinicians use standardized screening tools such as the Confusion Assessment Method (Confusion Assessment Method) or its bedside adaptations like CAM-ICU (CAM-ICU) and shorter tools such as the 4AT (4AT). Diagnostic criteria typically require: - An acute change in attention and a disturbance in awareness - A fluctuating course during the day - Additional disturbance in cognition (memory, language, visuospatial ability) not better explained by another neurocognitive disorder - Evidence that the disturbance is a direct physiological consequence of another medical condition, substance use, or medication effect

Imaging and laboratory tests are guided by suspected underlying etiologies and may include investigations for infection, metabolic derangements, renal or hepatic dysfunction, electrolyte abnormalities, and medication toxicity.

Classification and subtypes

  • Hyperactive delirium: marked agitation, restlessness, and overt motor behavior
  • Hypoactive delirium: diminished level of activity, apathy, and reduced responsiveness (often underdiagnosed)
  • Mixed delirium: alternating hyperactive and hypoactive features

Pathophysiology

Delirium reflects widespread brain dysfunction rather than a single lesion. Converging theories point to: - Neurotransmitter imbalances, notably cholinergic deficiency and dopaminergic excess - Neuroinflammation and inflammatory mediators that affect neuronal signaling - Disruption of large-scale brain networks involved in attention, awareness, and executive function - Sleep disruption and sensory deprivation that amplify cognitive vulnerability The precise mix of mechanisms varies with the patient and the underlying trigger, which is why treating delirium effectively requires addressing the root cause(s) in addition to managing symptoms.

Prevention

Preventive measures aim to reduce exposure to delirium triggers and support brain function during acute illness or hospitalization: - Early mobilization and physical activity - Adequate hydration, nutrition, and pain control - Sleep promotion and wakeful rest schedules - Correction of sensory deficits (glasses, hearing devices) - Minimizing polypharmacy and avoiding deliriogenic medications when possible - Routine delirium screening for at-risk patients These strategies have been associated with lower delirium incidence and improved outcomes in many care settings, including general wards and the ICU. See Sleep deprivation and Geriatrics for related topics on aging and hospital care.

Management

The cornerstone of delirium care is prompt identification and treatment of the underlying cause(s), combined with supportive measures to ensure safety and comfort: - Comprehensive medical assessment to identify infection, metabolic disturbance, organ dysfunction, hypoxia, or medication issues - Optimization of hydration, nutrition, pain control, and sleep, with environmental orientation and meaningful engagement - Minimize exposure to deliriogenic drugs; avoid or limit anticholinergics, benzodiazepines (except in alcohol or benzodiazepine withdrawal delirium), and unnecessary sedatives - Nonpharmacologic interventions (reorientation, presence of family members, familiar routines) - Pharmacologic treatment only when agitation poses a safety risk or when nonpharmacologic approaches fail; preferred agents include low-dose antipsychotics such as haloperidol or atypical antipsychotics like quetiapine, with careful monitoring for adverse effects - Special considerations for delirium in the ICU, including delirium-directed sedation strategies and daily sedation vacations For a detailed pharmacologic overview, see Haloperidol and Antipsychotics.

Prognosis and outcomes

Delirium is associated with adverse short- and long-term outcomes: - Prolonged hospitalization and higher in-hospital mortality - Increased risk of complications such as falls, malnutrition, and infections - Greater likelihood of cognitive decline and new or worsened dependence after discharge - In some patients, delirium resolves with treatment of the underlying illness, but in others it may herald longer-term neurocognitive sequelae The course of delirium is highly variable and depends on the patient’s age, baseline cognitive reserve, and the timeliness and effectiveness of management.

Controversies and debates

Delirium care sits at the intersection of medicine, hospital administration, and public policy, with several ongoing debates: - Screening and diagnosis: universal screening in hospitals can improve detection but requires resources and consistent implementation; critics worry about overdiagnosis or alarmism if criteria are not applied carefully. Proponents argue that early detection reduces complications and length of stay. - Pharmacologic management: the use of antipsychotics in delirium is common, but evidence is mixed regarding long-term outcomes and mortality. Some clinicians emphasize minimizing drugs that can worsen delirium, especially benzodiazepines, while others argue for targeted use in specific situations (e.g., withdrawal syndromes). See Haloperidol. - Nonpharmacological emphasis vs. clinical efficiency: advocates of stringent nonpharmacologic protocols emphasize patient safety, family involvement, and environmental modification; critics worry about workflow burden and potential delays in treating acute medical issues. - Patient autonomy and safety: balancing safety with respect for patient preferences can raise questions about restraints, sedation, and family involvement. In practice, most clinicians favor approaches that reduce delirium risk while preserving dignity and independence as much as possible. - Cultural critiques and practical realities: some observers frame delirium initiatives within broader social debates about medicalization or resource allocation. From a practical clinical standpoint, the strongest evidence supports addressing immediate medical causes, minimizing iatrogenic risks, and using structured approaches to reduce delirium incidence and its consequences.

See also