• A temporary neurocognitive complication of illness and/or medication(s) manifested by new confusion and impaired attention
  • Requires evaluation to decrease morbidity and mortality


  • Predominant age: older persons
  • Predominant sex: male = female


  • >50% in older ICU patients
  • 11–51% in postoperative patients
  • 19% after intracranial surgery and 42% after neurovascular surgery
  • 10–40% in hospitalized older patients
  • 20–22 % in nursing home/post–acute care patients


  • 1–2% in outpatients
  • 8–17% in older ED patients

Etiology and Pathophysiology

  • Multifactorial: believed to result from a decline in physiologic reserves with aging, resulting in a vulnerability to new stressors
  • Often interaction between predisposing and precipitating risk factors

Risk Factors

  • Predisposing risk factors
    • Advanced age, >70 years
    • Preexisting cognitive impairment
    • Functional impairment
    • Dehydration
    • History of alcohol abuse
    • Malnutrition
    • Hearing or vision impairment
    • Multiple comorbidities
  • Precipitating risk factors
    • Severe illness in any organ system
    • Medical devices (urinary catheter, restraints)
    • Polypharmacy (≥5 medications)
    • Specific medications, especially benzodiazepines, opioids, anticholinergics diphenhydramine, high-dose neuroleptics
    • Pain
    • Any iatrogenic event
    • Surgery
    • Sleep deprivation

Commonly Associated Conditions

Multiple but most common are the following:

  • Medication changes
  • Infections (especially lung, urine, and bloodstream, but consider meningitis as well)
  • Toxic metabolic (especially low sodium, elevated calcium, renal failure, and hepatic failure)
  • Heart attack or stroke
  • Alcohol or drug withdrawal
  • Preexisting cognitive impairment increases risk.

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