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Delirium (PDQ®)

Health Professional Version

Assessment, Diagnosis, and Monitoring

The diagnosis of delirium should be considered for any patient with cancer demonstrating the following:

  • An acute onset of agitation or uncooperative behavior.
  • A personality change.
  • Impaired cognitive functioning.
  • Altered attention span.
  • Fluctuating level of consciousness.
  • Uncharacteristic anxiety or depression.

However, the diagnoses of delirium and cognitive impairment are frequently missed and poorly documented.[1-5]

Medical and nursing staff, as well as family members, may attribute a functional cause to some of the early, prodromal, and more subtle signs of delirium such as increased anxiety, restlessness, and emotional lability.[6] Failure to recognize delirium is particularly likely if the patient is encountered in a transient lucid phase, which can commonly occur as part of the fluctuating nature of delirium.[7] Delirium is most frequently misdiagnosed as depression or dementia.[7-10] The hypoactive subtype is considered especially likely to be misdiagnosed as depression.[7]

Differentiating delirium from dementia or recognizing delirium superimposed on dementia can be difficult because of some shared clinical features such as disorientation and impairment of memory, thinking, and judgment.[11-13] However, dementia typically appears in relatively alert individuals; disturbance of consciousness is not a common feature. The temporal onset of symptoms of delirium is acute (hours to days), not insidious (months to years) as in dementia.[14] In elderly patients with cancer, delirium is often superimposed on dementia, giving rise to a particularly difficult diagnostic challenge. In this situation, the diagnosis may become more apparent when delirium fails to reverse or when some features of delirium, especially cognitive impairment, persist. Dementia is often then the most likely explanation for a persistent or residual cognitive deficit.[14]

Vigilance on the part of nursing staff and a systematic approach to recording serial observations assist in the detection of delirium. Regular cognitive screening facilitates the diagnosis of delirium in cancer patients.[15]

Instruments that have favorable psychometric properties and are brief enough to allow repeated administration in cancer patients include the following:[16-21]

  • The Mini-Mental State Examination (MMSE) screens for cognitive impairment and requires active patient participation in assessment.
  • The Blessed Orientation Memory and Concentration Test (BOMC) screens for cognitive impairment and requires active patient participation in assessment.
  • The Confusion Assessment Method (CAM) screens for cognitive impairment but does not require formal patient participation.
  • The Bedside Confusion Scale requires active patient participation and is remarkably brief; its psychometric potential as a screening instrument compares favorably with the CAM.
  • The Memorial Delirium Assessment Scale (MDAS) has been validated as having diagnostic and severity rating potential. This scale allows prorating of scores when a patient cannot actively participate in testing for reasons such as dyspnea or fatigue.
  • The Delirium Rating Scale-Revised-98 has been validated as having diagnostic and severity rating potential.


  1. McCartney JR, Palmateer LM: Assessment of cognitive deficit in geriatric patients. A study of physician behavior. J Am Geriatr Soc 33 (7): 467-71, 1985. [PUBMED Abstract]
  2. Harwood DM, Hope T, Jacoby R: Cognitive impairment in medical inpatients. II: Do physicians miss cognitive impairment? Age Ageing 26 (1): 37-9, 1997. [PUBMED Abstract]
  3. Hustey FM, Meldon SW: The prevalence and documentation of impaired mental status in elderly emergency department patients. Ann Emerg Med 39 (3): 248-53, 2002. [PUBMED Abstract]
  4. Rincon HG, Granados M, Unutzer J, et al.: Prevalence, detection and treatment of anxiety, depression, and delirium in the adult critical care unit. Psychosomatics 42 (5): 391-6, 2001 Sep-Oct. [PUBMED Abstract]
  5. Inouye SK, Foreman MD, Mion LC, et al.: Nurses' recognition of delirium and its symptoms: comparison of nurse and researcher ratings. Arch Intern Med 161 (20): 2467-73, 2001. [PUBMED Abstract]
  6. Breitbart W, Chochinov HM, Passik S: Psychiatric aspects of palliative care. In: Doyle D, Hanks GW, MacDonald N, eds.: Oxford Textbook of Palliative Medicine. 2nd ed. New York, NY: Oxford University Press, 1998, pp 933-56.
  7. Inouye SK: The dilemma of delirium: clinical and research controversies regarding diagnosis and evaluation of delirium in hospitalized elderly medical patients. Am J Med 97 (3): 278-88, 1994. [PUBMED Abstract]
  8. Nicholas LM, Lindsey BA: Delirium presenting with symptoms of depression. Psychosomatics 36 (5): 471-9, 1995 Sep-Oct. [PUBMED Abstract]
  9. Farrell KR, Ganzini L: Misdiagnosing delirium as depression in medically ill elderly patients. Arch Intern Med 155 (22): 2459-64, 1995 Dec 11-25. [PUBMED Abstract]
  10. Armstrong SC, Cozza KL, Watanabe KS: The misdiagnosis of delirium. Psychosomatics 38 (5): 433-9, 1997 Sep-Oct. [PUBMED Abstract]
  11. Fick D, Foreman M: Consequences of not recognizing delirium superimposed on dementia in hospitalized elderly individuals. J Gerontol Nurs 26 (1): 30-40, 2000. [PUBMED Abstract]
  12. Johnson J, Sims R, Gottlieb G: Differential diagnosis of dementia, delirium and depression. Implications for drug therapy. Drugs Aging 5 (6): 431-45, 1994. [PUBMED Abstract]
  13. Cole MG, McCusker J, Dendukuri N, et al.: Symptoms of delirium among elderly medical inpatients with or without dementia. J Neuropsychiatry Clin Neurosci 14 (2): 167-75, 2002 Spring. [PUBMED Abstract]
  14. Lipowski ZJ: Delirium in the elderly patient. N Engl J Med 320 (9): 578-82, 1989. [PUBMED Abstract]
  15. Bruera E, Miller L, McCallion J, et al.: Cognitive failure in patients with terminal cancer: a prospective study. J Pain Symptom Manage 7 (4): 192-5, 1992. [PUBMED Abstract]
  16. Folstein MF, Folstein SE, McHugh PR: "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 12 (3): 189-98, 1975. [PUBMED Abstract]
  17. Inouye SK, van Dyck CH, Alessi CA, et al.: Clarifying confusion: the confusion assessment method. A new method for detection of delirium. Ann Intern Med 113 (12): 941-8, 1990. [PUBMED Abstract]
  18. Katzman R, Brown T, Fuld P, et al.: Validation of a short Orientation-Memory-Concentration Test of cognitive impairment. Am J Psychiatry 140 (6): 734-9, 1983. [PUBMED Abstract]
  19. Stillman MJ, Rybicki LA: The bedside confusion scale: development of a portable bedside test for confusion and its application to the palliative medicine population. J Palliat Med 3 (4): 449-56, 2000.
  20. Trzepacz PT, Mittal D, Torres R, et al.: Validation of the Delirium Rating Scale-revised-98: comparison with the delirium rating scale and the cognitive test for delirium. J Neuropsychiatry Clin Neurosci 13 (2): 229-42, 2001 Spring. [PUBMED Abstract]
  21. Breitbart W, Rosenfeld B, Roth A, et al.: The Memorial Delirium Assessment Scale. J Pain Symptom Manage 13 (3): 128-37, 1997. [PUBMED Abstract]
  • Updated: July 30, 2014