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For further information, see CMDT Part 4-04: Management of Common Geriatric Problems

Key Features

Essentials of Diagnosis

  • Rapid onset and fluctuating course

  • Primary deficit is in attention rather than memory

  • May be hypoactive or hyperactive

  • Dementia frequently coexists

General Considerations

  • Delirium is the pathophysiologic consequence of an underlying general medical condition such as

    • Infection

    • Hypoxemia

    • Metabolic derangement

    • Coronary ischemia

  • Although the acutely agitated (hyperactive) elderly patient often comes to mind when considering delirium, many episodes are more subtle (hypoactive)

  • A key requirement is review of medications

  • Maintenance of a large number of drugs, addition of a new agent, and discontinuation of an agent known to cause withdrawal symptoms are often associated with development of delirium

  • Medications that are particularly likely to increase the risk of delirium include

    • Sedative/hypnotics

    • Anticholinergics

    • Opioids

    • Benzodiazepines

    • H1- and H2-antihistamines

  • Cognitive impairment is an important risk factor for delirium

  • Other risk factors

    • Severe illness

    • Polypharmacy and use of psychoactive medications

    • Sensory impairment

    • Depression

    • Alcohol use disorder


  • Occurs in 29–64% of hospitalized older adults

  • Persists in 25% or more

Clinical Findings

Symptoms and Signs

  • Acute, fluctuating disturbance of consciousness or mental status

  • Inattention, inability to focus on tasks

  • Cognitive deficits, disorientation, memory and language impairment

  • Irritability

  • Hyperactivity or hypoactivity

  • Mental slowing

  • Hallucinations or illusions

Differential Diagnosis

  • Once the diagnosis of delirium has been made, an underlying cause should be sought. The underlying causes are wide-ranging.

  • Depression

  • Mania

  • Dementia, especially Lewy body dementia

  • Psychotic disorders

  • Seizures


Laboratory Tests

  • Laboratory evaluation is aimed at finding an underlying medical condition

  • Routine studies include

    • Complete blood count

    • Serum electrolytes, creatinine, glucose, calcium, albumin, liver biochemical tests; blood urea nitrogen

    • Urinalysis

    • ECG

  • In selected cases, serum magnesium, drug levels, arterial blood gas measurements, blood cultures, chest radiographs, urinary toxin screens, head CT scan, and lumbar puncture may be helpful

Imaging Studies

  • Consider neuroimaging if unable to obtain history, if evidence of trauma, or if focal neurologic examination

Diagnostic Procedures

  • Electroencephalogram may sometimes be helpful if seizures are in the differential diagnosis

  • Confusion assessment method (CAM)

    • Requires acute onset and fluctuating course, inattention, and either disorganized thinking or altered level of consciousness

    • Available as Long CAM, Short CAM, and 3D CAM (3-minute Diagnostic CAM)

    • All three perform well

    • The 3D CAM is particularly useful for the clinical assessment of delirium

    • Two variations, the CAM-ICU and the CAM-S, are useful for the intensive care unit setting and in assessing delirium severity, respectively




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