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DEFINITION

The neurocognitive disorders (NCDs) comprise a group of conditions defined by decline from a previous level of cognitive functioning. The six cognitive domains that may be affected include complex attention, executive function, learning and memory, language, perceptual-motor skills, and social cognition (interaction). By definition, cause(s) for the deficits may be ascertained from findings on history, physical exam, and diagnostic testing. The DSM-5 divides the NCDs into three main categories: delirium, mild NCDs, and major NCDs (dementias).

DELIRIUM

  • Delirium is a medical emergency.

  • May be the only early manifestation of serious illness.

  • Potentially reversible.

  • Can advance to coma, seizures, or death.

  • Associated with high mortality. Up to 40% of individuals die within 1 year of diagnosis.

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Terms commonly used for delirium include toxic or metabolic encephalopathy, acute organic brain syndrome, acute confusional state, acute toxic psychosis, and ICU psychosis.

Epidemiology

  • Up to one-half of hospitalized elderly patients develop delirium.

  • As many as 90% of patients with a preexisting NCD (dementia) will experience a superimposed delirium when admitted to the hospital.

  • Delirium often goes unrecognized (65–88% of the time).

  • Delirium is associated with an increased risk for later development of major NCD.

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Consider delirium as acute brain failure—a medical emergency like other acute organ failures.

Risk Factors

  • Advanced age.

  • Preexisting cognitive impairment or depression.

  • Prior history of delirium.

  • Severe or terminal illness.

  • Multiple medical comorbidities.

  • Hearing or vision impairment.

image  WARDS QUESTION

Q: What is the “ICU triad?”

A: Pain, Agitation, and Delirium.

Precipitating Factors

  • Polypharmacy, including the use of psychotropic medications (especially benzodiazepines and anticholinergic drugs).

  • Alcohol use or withdrawal.

  • Infection.

  • Pain.

  • Dehydration.

  • Malnutrition.

  • Impaired mobility.

  • Sleep deprivation.

  • Organ failure.

  • Mechanical ventilation.

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Delirium is commonly experienced by patients in the ICU and postoperative recovery.

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Common causes of medication-induced delirium:

  • Anticholinergics

  • Benzodiazepines

  • Nonbenzodiazepine hypnotics (“Z-drugs”)

  • Opioids (especially meperidine)

  • Corticosteroids

  • Tricyclic antidepressants

  • H2 blockers

Etiology

  • Almost any medical condition can cause delirium (see examples in Table 8-1).

  • The DSM-5 recognizes five broad categories:

    • Substance intoxication delirium.

    • Substance withdrawal delirium.

    • Medication-induced delirium.

    • Delirium due to another medical condition.

    • Delirium due to multiple etiologies.

TABLE 8-1.Clinical Scenarios of Delirium on Exam

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