# Delirium

Delirium is an acute, fluctuating disturbance in attention and cognition that requires prompt bedside recognition, confirmation with structured assessment, and a search for reversible precipitants. Multicomponent prevention and careful attention to baseline cognition, medication exposure, hydration, mobility, sleep, and sensory impairment are central to care.

**Clinical question:** How should physicians identify, evaluate, prevent, and monitor delirium in hospitalized adults?

Updated: 2026-08-21T01:28:44.231088+00:00

## What matters in practice
- Diagnose delirium clinically by an acute, fluctuating change from baseline with inattention and altered awareness or cognition; structured tools support detection but do not replace clinician assessment. [11][13][16]
- The CAM requires acute onset/fluctuation and inattention plus either disorganized thinking or altered consciousness; CAM-ICU permits assessment in intubated ICU patients. [13][14][18]
- A positive screen should trigger urgent evaluation for reversible and often multiple precipitants rather than attribution to dementia, age, or hospitalization alone. [9][13][18]
- Multicomponent prevention targets modifiable risks, including sleep disruption, immobility, sensory impairment, dehydration, nutrition, oxygenation, medication exposure, mood, and bowel/bladder care. [1][19]
- Delirium is associated with longer hospitalization, functional decline, institutionalization, cognitive decline, dementia, and mortality; it should be treated as a major acute brain dysfunction. [4][18][20]

## Recognize delirium as acute brain dysfunction

Establish the time course and baseline cognitive and functional status before interpreting bedside findings.

Delirium is a clinical diagnosis. The core diagnostic phenotype is a disturbance in attention and awareness developing over hours to days, representing a change from baseline, fluctuating during the day, and accompanied by an additional cognitive disturbance. The syndrome cannot be better explained solely by a pre-existing neurocognitive disorder and should not be diagnosed in coma or markedly reduced arousal. [11][16][18]

Obtain collateral history from family, caregivers, outpatient records, nursing staff, and the prior clinical team. In older adults, pre-existing dementia complicates assessment but does not exclude delirium; the clinically decisive feature is an acute change from the patient's usual cognition, attention, arousal, or behavior. Lewy body dementia may itself fluctuate and therefore requires especially careful baseline characterization. [9][11]

Hypoactive presentations are easily missed. New drowsiness, reduced interaction, diminished ability to follow conversation, or failure to sustain attention warrants the same evaluation as agitation. In ICU populations, delirium is a common manifestation of acute brain dysfunction and may affect up to 83% of mechanically ventilated patients. [11][18]
- Document baseline cognition, recent trajectory, sensory deficits, sleep pattern, medication changes, substance exposure, pain, bowel and bladder status, and recent procedures or transfers. [1][13][19]
- Do not label an acute mental-status change as dementia progression without evidence that it reflects the patient's established baseline. [9][11]
- Reassess because fluctuation is intrinsic to delirium; a single normal examination does not exclude it. [11][16]

*Bedside features that distinguish delirium from chronic cognitive impairment. [9][11][16]*

| Feature | Delirium | Clinical implication |
| --- | --- | --- |
| Time course | Develops over hours to days and fluctuates. [11][16] | Seek an acute precipitant and compare with baseline. [11][13] |
| Attention | Impaired ability to direct, sustain, or shift attention. [11][16] | Test attention directly; it is central to diagnosis. [11][13] |
| Arousal | May be hypervigilant, drowsy, or stuporous. [11] | Hypoactive delirium requires active detection. [11] |
| Dementia overlap | May be superimposed on a neurocognitive disorder. [9][11] | Use collateral history to identify acute change; Lewy body dementia can fluctuate. [9] |

## Use a validated instrument to detect and communicate delirium

Choose a tool that matches the setting, workflow, and staff training.

DSM-5 and ICD criteria are reference standards, but routine identification depends on repeated bedside observation and brief cognitive assessment. The CAM is widely used and has four features: acute onset with fluctuating course, inattention, disorganized thinking, and altered level of consciousness. A CAM-positive result requires the first two features plus either disorganized thinking or altered consciousness. [11][13][14][16]

The 4AT is a brief assessment designed for general clinical settings and includes alertness, orientation using the Abbreviated Mental Test-4, attention using months backward, and acute change or fluctuation. It can be performed in less than 2 minutes and does not require specialized training. [9][13]

In ICU patients, CAM-ICU and the Intensive Care Delirium Screening Checklist are extensively validated and can be used when patients cannot speak because of endotracheal intubation. Screening should inform a clinical assessment and precipitant search; it is not a substitute for etiologic evaluation. [18]
- Use CAM when staff can perform the required cognitive assessment and apply its diagnostic algorithm. [14]
- Use 4AT when a rapid, low-training screening approach is needed on general wards or in acute care. [9][13]
- Use CAM-ICU or ICDSC for ICU patients, including mechanically ventilated patients. [18]
- A positive screen should prompt clinician confirmation, review of the trajectory, neurologic examination, and targeted evaluation for causes. [11][13]

### Interpreting discordant assessments

Tool performance varies by instrument, patient population, reference standard, and assessor training. In one surveillance summary, 4AT score greater than 3 had sensitivity 75.5% and specificity 96.4% for delirium, whereas short CAM had sensitivity 40% and specificity 100%; these findings should not be generalized as universal performance estimates across settings. [15]

If bedside concern persists despite a negative screen, repeat assessment during a different period of the day, obtain collateral information, and reassess for alternative acute neurologic, toxic, metabolic, infectious, or medication-related causes of altered mental status. [11][13][18]

*Common delirium assessment instruments and practical use. [9][13][14][18]*

| Instrument | Core elements | Best practical role |
| --- | --- | --- |
| CAM | Acute/fluctuating course, inattention, disorganized thinking, altered consciousness; positive when features 1 and 2 plus feature 3 or 4 are present. [14] | Structured bedside assessment when trained personnel can perform cognitive testing. [14] |
| 4AT | Alertness, AMT-4 orientation, months backward, and acute change or fluctuation. [9] | Rapid general-care screening without specialized training. [9][13] |
| CAM-ICU | ICU-adapted CAM assessment. [13][18] | Delirium detection in critically ill and nonverbal intubated patients. [18] |
| ICDSC | ICU delirium screening checklist. [18] | Serial ICU monitoring and assessment over time. [18] |

## Identify and reverse precipitating factors

Assume multifactorial causation until the clinical course and targeted evaluation support otherwise.

The mental-status examination may establish delirium, but the subsequent task is to identify its cause or causes. A thorough evaluation for reversible contributors is warranted even when no single etiology is immediately apparent. If the presumed precipitant is removed and delirium does not improve, expand or revisit the evaluation. [13][18]

Focus testing on findings from the history and examination rather than ordering a uniform laboratory or imaging panel. The assessment should account for medication exposure, pain, oxygenation, hydration and nutrition, infection or other systemic illness, metabolic disturbance, bowel and bladder problems, sensory impairment, sleep deprivation, immobility, and recent surgery or critical illness. [1][13][19]

Perform a focused neurologic examination and maintain a differential diagnosis for other causes of altered mental status. Delirium is a diagnosis of exclusion in ICU-focused references, and new confusion should not be presumed benign or attributed solely to chronic neurocognitive disease. [13][18]
- Review all recent medication additions, dose changes, sedative exposure, and nonprescription agents; medication review is a component of evidence-supported prevention approaches. [19]
- Assess and address pain, oxygenation, hydration, nutrition, constipation, urinary retention or other bladder care needs, mobility, sleep disruption, hearing, and vision. [1][19]
- When baseline cognition is uncertain, obtain informant history rather than relying on a single orientation test. [11][14]

*High-yield reversible domains in delirium evaluation and prevention. [1][13][19]*

| Domain | What to assess | Immediate clinical response |
| --- | --- | --- |
| Medication exposure | Recent additions or dose changes; sedating or otherwise high-risk medication burden. [13][19] | Perform a medication review and remove or reduce plausible contributors when clinically feasible. [19] |
| Physiologic support | Oxygenation, hydration, nutrition, and systemic illness. [19] | Correct documented abnormalities and reassess mental status over time. [13][19] |
| Comfort and elimination | Pain, bowel function, bladder care, and urinary retention concerns. [19] | Treat identified contributors and minimize avoidable discomfort. [19] |
| Environment and function | Sleep loss, immobility, visual impairment, and hearing impairment. [1][19] | Implement sleep, mobility, and sensory-support measures. [1][19] |

## Prioritize multicomponent nonpharmacologic care

Prevention and treatment should be integrated with correction of active precipitants.

Multicomponent prevention addresses modifiable vulnerabilities and hospital exposures. In a seminal intervention study, cognitive impairment, sleep deprivation, immobility, visual impairment, hearing impairment, and dehydration were identified as delirium risk factors targeted by the intervention. [1]

A systematic review found that attention to nutrition and hydration, oxygenation, medication review, mood assessment, and bowel and bladder care was probably associated with prevention benefit. These measures are operationally useful because they also identify potentially reversible drivers in patients with established delirium. [19]

For high-risk surgical patients, the American College of Surgeons identifies age, alcohol use, poor cognitive or physical function, and abnormal laboratory findings as risk factors, and states that targeted interventions may prevent or lessen postoperative delirium. [22]
- Mobilize when clinically safe and avoid unnecessary immobility. [1]
- Support sleep and reduce avoidable sleep deprivation. [1]
- Ensure access to hearing and visual aids when applicable. [1]
- Monitor hydration, nutrition, oxygenation, pain, medication burden, bowel function, and bladder care. [19]
- Identify high-risk surgical patients before the procedure and apply targeted preventive measures. [22]

### Pharmacologic treatment evidence

The supplied evidence does not support a medication-specific routine treatment regimen, dose, or prophylactic drug strategy for delirium. Although dexmedetomidine has been studied for ICU delirium prevention, the available result describes an internally validated reinforcement-learning dosing model rather than clinical guidance establishing a standard dose or indication. [3]

Do not infer that a screening tool or a delirium diagnosis alone establishes an indication for drug therapy. Medication decisions should instead be individualized to the precipitating condition, immediate safety needs, setting, and current institutional or specialty guidance, which cannot be specified from the supplied sources. [13][18][21]

*Multicomponent measures with evidence-supported preventive relevance. [1][19][22]*

| Measure | Targeted risk or contributor | Population or setting |
| --- | --- | --- |
| Sleep support | Sleep deprivation. [1] | Hospitalized patients at risk for delirium. [1] |
| Early mobility support | Immobility. [1] | Hospitalized patients at risk for delirium. [1] |
| Vision and hearing support | Visual and hearing impairment. [1] | Patients with sensory impairment. [1] |
| Hydration and nutrition attention | Dehydration and nutritional vulnerability. [1][19] | Hospitalized patients at risk for or with delirium. [1][19] |
| Medication, bowel, bladder, mood, and oxygenation review | Potential modifiable contributors. [19] | Hospitalized patients at risk for delirium. [19] |

## Communicate delirium as a marker of substantial risk

Resolution of inattention or agitation does not erase the associated short- and long-term vulnerability.

Delirium is associated with longer hospital stay, lower six-month survival in ICU-focused evidence, and long-term cognitive impairment among critical illness survivors. [18] In older adults, delirium has also been associated with postdischarge mortality, institutionalization, and dementia independent of important confounders in a meta-analysis. [4]

Postoperative delirium is associated with subsequent adverse cognitive trajectories, and delirium is linked to functional decline, readmissions, institutionalization, cognitive decline, dementia, and mortality in broader clinical literature summaries. [2][20] These associations do not establish that every outcome is directly caused by delirium, but they justify explicit discharge communication and follow-up planning.

At discharge, document the delirium episode, suspected or confirmed precipitants, baseline cognitive uncertainty, residual cognitive or functional deficits, and needed supervision or support. For patients with persistent symptoms or incomplete recovery, arrange reassessment rather than assuming return to baseline. [13][18][20]
- Communicate delirium history during transitions of care because it signals elevated vulnerability after hospitalization. [4][20]
- Assess function and cognition during recovery, particularly after critical illness or postoperative delirium. [2][18]
- Reevaluate persistent cognitive change for unresolved precipitants or alternative diagnoses. [13]

*Outcome associations relevant to discharge planning. [2][4][18][20]*

| Outcome domain | Association reported | Practical implication |
| --- | --- | --- |
| Hospital course | Longer hospital stay is associated with delirium. [18] | Plan for increased care complexity and reassess mobility, cognition, and disposition needs. [20] |
| Survival | Six-month survival is lower in ICU patients with delirium than in those without delirium. [18] | Frame delirium as a clinically consequential complication, not a transient inconvenience. [18] |
| Cognition | Long-term cognitive impairment and adverse cognitive trajectories are associated with delirium. [2][18] | Document baseline and recovery status; arrange follow-up when deficits persist. [2][18] |
| Postdischarge independence | Institutionalization and functional decline are associated with delirium. [4][20] | Include caregivers and disposition teams early. [20] |

## Common questions

### Can delirium be diagnosed in a patient with dementia?

Yes. Dementia does not exclude delirium. Diagnose delirium when there is an acute, fluctuating change from baseline with inattention and altered awareness or cognition; collateral history is essential. Lewy body dementia can have intrinsic cognitive fluctuations. [9][11][16]

### What is the most useful bedside screening tool for delirium?

There is no single best tool for every setting. CAM is widely used when trained staff can apply its algorithm; 4AT is rapid and requires no specialized training; CAM-ICU and ICDSC are appropriate in ICU patients, including those unable to speak because of intubation. [9][14][18]

### What should follow a positive delirium screen?

Confirm the acute change clinically, establish baseline from collateral sources, perform focused neurologic and medical assessment, review medications, and evaluate reversible contributors such as oxygenation, hydration, pain, elimination problems, sleep loss, immobility, and sensory deficits. [11][13][19]

### Are medications routinely indicated to treat delirium?

The supplied sources do not establish a routine medication regimen, dose, or prophylactic pharmacotherapy strategy. Prioritize correction of precipitants and multicomponent nonpharmacologic care; medication decisions require patient-specific assessment and current local or specialty guidance. [3][19][21]

## References
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2. Cognitive Trajectories after Postoperative Delirium — www.nejm.org — https://www.nejm.org/doi/full/10.1056/NEJMoa1112923
3. Reinforcement learning model for optimizing dexmedetomidine dosing to prevent delirium in critically ill patients | npj Digital Medicine — www.nature.com — https://www.nature.com/articles/s41746-024-01335-x
4. Delirium | Nature Reviews Disease Primers — www.nature.com — https://www.nature.com/articles/s41572-020-00223-4
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6. Long-term clinical outcomes of delirium after hospital discharge — academic.oup.com — https://academic.oup.com/ageing/article/54/7/afaf188/8193852
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9. Differentiating Delirium Versus Dementia in Older Adults - StatPearls - NCBI Bookshelf — www.ncbi.nlm.nih.gov — https://www.ncbi.nlm.nih.gov/books/NBK570594
10. Delirium: prevention, diagnosis and management — www.nice.org.uk — https://www.nice.org.uk/guidance/cg103/evidence/a-diagnostic-accuracy-of-tests-to-identify-delirium-pdf-11320715486
11. Delirium in Older Persons: Advances in Diagnosis and Treatment - PMC — pmc.ncbi.nlm.nih.gov — https://pmc.ncbi.nlm.nih.gov/articles/PMC5717753
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15. 2020 exceptional surveillance of delirium: prevention, ... — www.nice.org.uk — https://www.nice.org.uk/guidance/cg103/resources/2020-exceptional-surveillance-of-delirium-prevention-diagnosis-and-management-nice-guideline-cg103-pdf-11441240136133
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17. RESULTS - Delirium: Screening, Prevention, and Diagnosis – A Systematic Review of the Evidence - NCBI Bookshelf — www.ncbi.nlm.nih.gov — https://www.ncbi.nlm.nih.gov/books/NBK82558
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22. Strong for Surgery | ACS — www.facs.org — https://www.facs.org/quality-programs/qi-resources/strong-for-surgery
23. World delirium awareness and quality survey in 2023—a ... — academic.oup.com — https://academic.oup.com/ageing/article/53/11/afae248/7905759
24. Knowledge translation for delirium superimposed on dementia ... — academic.oup.com — https://academic.oup.com/gerontologist/article/66/6/gnag071/8665112

## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.