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In medicine, delirium is a "disorder characterized by confusion; inattentiveness; disorientation; illusions; hallucinations; agitation; and in some instances autonomic nervous system overactivity )."[1][2]

According to the Diagnostic and Statistical Manual of Mental Disorders, delirium is "reduced ability to think or concentrate, restlessness, anxiety, irritability, drowsiness, hypersensitivity to stimuli, nightmares."[3]

Etiology / cause

Dysglycemia may contribute to delirium.[4]


This topic has been reviewed.[5][6]

Among hospitalized geriatric patients, "failure to identify either year or month correctly was 95% sensitive and 86.5% specific for the detection of cognitive impairment".[7]

Specific disorders such as substance withdrawal syndrome, intoxication, Wernicke encephalopathy, and osmotic demyelination syndrome (central pontine myelinolysis) should be excluded.

Confusion Assessment Method (CAM)

The confusion assessment method (CAM), which is an algorithm with four criteria based on the Diagnostic and Statistical Manual of Mental Disorders can help diagnose when the first two criteria are present and either the third or fourth criteria is present:[8][5]

  1. acute onset and fluctuating course
  2. inattention
  3. disorganized thinking
  4. altered level of consciousness

In the CAM-S, items 2-3 are rated as 0 (absent), 1 (mild), or 2 (marked). For the first item, acute onset and fluctuation was rated 0 (absent) or 1 (present).[9] In this study, no cut off score reliably diagnosed delirium, but a score of less than 2 was rarely associated with delirium that was independently diagnosed.

Mini-mental state examination (MMSE)

The Mini-mental state examination (MMSE) can also help and can be found in the appendix of its original publication.[10]

Components of the MMSE have been studied:

Component Sensitivity Specificity
Three item recall[11] 54% 96%
Disorientation to year[7] 86% 94%
Counting backwards cell cell

Six item screener (SIS)

The examiner first asks the patient to remember three items: GRASS PAPER SHOE. The examiner can repeat the words 3 times as needed to help the patient.[12]

Orientation to time

  • Year
  • Month
  • Day of the week

Recall of three items (one point each)

  • Sensitivity 74%
  • Specificity 77%

Subsyndromal delirium

Subsyndromal delirium may cause morbidity among hospitalized individuals.[3]


For patients who have agitation, randomized controlled trials have found that:

Antipsychotic agents, such as haloperidol less than 3.0 mg per day, can improve delirium according to a systematic review by the Cochrane Collaboration.[15] Haloperiderol may be best.[16]

Cholinesterase inhibitors like donepezil do not clearly help, but they have not been well studied.[17]

Benzodiazepines may worsen delirium[18] and no evidence supports their use.[19]


Clinical practice guidelines by National Institute for Health and Clinical Excellence direct prevention.[20]

Who is at risk?

The strongest risk factors for developing delirium are impaired cognition and psychotropic drug use.[21]

Clinical prediction rule have been developed to help the prediction.

Inouye et al studied hospitalized geriatric patients and assigned one point to each of the following:[22]

  • vision impairment
  • severe illness as defined by APACHE II score of 17 or more
  • cognitive impairment. Score of 23 or less on the Mini-Mental State Examination (MMSE). The MMSE can be found in the appendix of its original publication.[10]
  • high blood urea nitrogen/creatinine ratio of 18 or more

The rates of delirium were:[22]

  • 0 points 3%
  • 1-2 points 16%
  • 3-4 points 32%

These results have been independently validated with respective incidences of delirium of 4%, 12%, and 38%.[23]

Rudolph et al studied geriatric patients undergoing cardiac surgery and used four following predictors: abnormal Mini Mental State Examination, abnormal Geriatric Depression Scale prior cerebrovascular disease, and abnormal serum albumin.[24] This rule has not been independently validated.


"Proactive geriatric consultation may reduce delirium incidence and severity...prophylactic low dose haloperidol may reduce severity and duration of delirium episodes according to a systematic review by the Cochrane Collaboration."[25]

In hip surgery (about 25% were for hip fracture), geriatric patients with at least one point on the Inouye prediction rule (see above), haloperidol 1.5 mg per day was started on admission and continued until 3 days after surgery reduced the severity and duration of delirium.[23] The incidence of delirium was insignificantly reduced from 15.1% and 16.5% to 15.1%. However, for secondary outcomes, the duration of delirium was reduced by 6 days and the duration of hospitalization was significantly reduced by 5 days. There were no drug-related side effects. Patients in both the treatment and control groups received geriatric consultation.

Also in surgery of hip fracture, the use of light sedation with propofol may reduce postoperative delirium in geriatric patients as compared with deep sedation.[26]


Many geriatrics patients have delirium persist at hospital discharge and for months afterwards.[27]


  1. Anonymous (2023), Delirium (English). Medical Subject Headings. U.S. National Library of Medicine.
  2. Breitbart, William; Yesne Alici (2008-12-24). "Agitation and Delirium at the End of Life: "We Couldn't Manage Him"". JAMA 300 (24): 2898-2910. DOI:10.1001/jama.2008.885. Retrieved on 2009-01-07. Research Blogging.
  3. 3.0 3.1 Cole M, McCusker J, Dendukuri N, Han L (June 2003). "The prognostic significance of subsyndromal delirium in elderly medical inpatients". J Am Geriatr Soc 51 (6): 754–60. PMID 12757560[e]
  4. Duning T, van den Heuvel I, Dickmann A, Volkert T, Wempe C, Reinholz J et al. (2010). "Hypoglycemia aggravates critical illness-induced neurocognitive dysfunction.". Diabetes Care 33 (3): 639-44. DOI:10.2337/dc09-1740. PMID 20032274. PMC PMC2827523. Research Blogging.
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  6. Mitchell AJ, Malladi S (2010). "Screening and case-finding tools for the detection of dementia. Part II: evidence-based meta-analysis of single-domain tests.". Am J Geriatr Psychiatry 18 (9): 783-800. DOI:10.1097/JGP.0b013e3181cdecd6. PMID 20808094. Research Blogging.
  7. 7.0 7.1 O'Keeffe E, Mukhtar O, O'Keeffe ST (2011). "Orientation to time as a guide to the presence and severity of cognitive impairment in older hospital patients.". J Neurol Neurosurg Psychiatry 82 (5): 500-4. DOI:10.1136/jnnp.2010.214817. PMID 20852313. Research Blogging.
  8. Inouye SK, van Dyck CH, Alessi CA, Balkin S, Siegal AP, Horwitz RI (December 1990). "Clarifying confusion: the confusion assessment method. A new method for detection of delirium". Ann. Intern. Med. 113 (12): 941–8. PMID 2240918[e]
  9. Inouye SK, Kosar CM, Tommet D, Schmitt EM, Puelle MR, Saczynski JS et al. (2014). "The CAM-S: development and validation of a new scoring system for delirium severity in 2 cohorts.". Ann Intern Med 160 (8): 526-33. DOI:10.7326/M13-1927. PMID 24733193. Research Blogging.
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  13. Agar MR, Lawlor PG, Quinn S, Draper B, Caplan GA, Rowett D et al. (2016). "Efficacy of Oral Risperidone, Haloperidol, or Placebo for Symptoms of Delirium Among Patients in Palliative Care: A Randomized Clinical Trial.". JAMA Intern Med. DOI:10.1001/jamainternmed.2016.7491. PMID 27918778. Research Blogging.
  14. Taylor DM, Yap CY, Knott JC, Taylor SE, Phillips GA, Karro J et al. (2016). "Midazolam-Droperidol, Droperidol, or Olanzapine for Acute Agitation: A Randomized Clinical Trial.". Ann Emerg Med. DOI:10.1016/j.annemergmed.2016.07.033. PMID 27745766. Research Blogging.
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  17. Overshott R, Karim S, Burns A (2008). "Cholinesterase inhibitors for delirium". Cochrane Database Syst Rev (1): CD005317. DOI:10.1002/14651858.CD005317.pub2. PMID 18254077. Research Blogging.
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  23. 23.0 23.1 Kalisvaart KJ, de Jonghe JF, Bogaards MJ, et al (October 2005). "Haloperidol prophylaxis for elderly hip-surgery patients at risk for delirium: a randomized placebo-controlled study". J Am Geriatr Soc 53 (10): 1658–66. DOI:10.1111/j.1532-5415.2005.53503.x. PMID 16181163. Research Blogging.
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  25. Siddiqi N, Stockdale R, Britton AM, Holmes J (2007). "Interventions for preventing delirium in hospitalised patients". Cochrane Database Syst Rev (2): CD005563. DOI:10.1002/14651858.CD005563.pub2. PMID 17443600. Research Blogging.
  26. Sieber FE, Zakriya KJ, Gottschalk A, Blute MR, Lee HB, Rosenberg PB et al. (2010). "Sedation depth during spinal anesthesia and the development of postoperative delirium in elderly patients undergoing hip fracture repair.". Mayo Clin Proc 85 (1): 18-26. DOI:10.4065/mcp.2009.0469. PMID 20042557. PMC PMC2800291. Research Blogging.
  27. Cole MG, Ciampi A, Belzile E, Zhong L (January 2009). "Persistent delirium in older hospital patients: a systematic review of frequency and prognosis". Age Ageing 38 (1): 19–26. DOI:10.1093/ageing/afn253. PMID 19017678. Research Blogging.