Delirium

ICD-10F05	Delirium, not induced by alcohol and other psychoactive substances
DSM-5-TRF05	Delirium

1. Definition and nosology

Delirium (ICD-11: 6D70; DSM-5-TR: F05) — a neuropsychiatric syndrome characterized by an acute, fluctuating disturbance of attention and consciousness, cognitive deficit (memory, orientation, language, visuospatial) and perceptual disturbances (illusions, hallucinations). Develops in response to a common medical cause (infection, medication, metabolic, neurological).

This is a medical emergency — the mortality rate for hospitalized elderly patients is 25–33%.

2. History

• Hippocrates “phrenitis” — classic description of delirium.
• Lipowski Z.J. (1980s–1990s) — modern conceptualization.
• CAM (Confusion Assessment Method, Inouye S.K. 1990) — gold standard screening.

3. Epidemiology

• Prevalence in hospitalized elderly 15–30%; in ICU 50–80%; post-surgery 15–50%.
• Comorbidity: dementia (delirium superimposed on dementia), infection, polypharmacy.
• Mortality and morbidity high; risk of long-term cognitive decline.

4. Etiology and pathogenesis

• Multiple factors:
  • Infections — sepsis, pneumonia, UTI;
  • Medication — anticholinergics, opioids, benzodiazepines, steroids;
  • Substance withdrawal (alcohol, benzodiazepine);
  • Metabolic — electrolyte, glucose, ammonia, uremia;
  • Hypoxia, hypoperfusion;
  • Neurological — seizure, stroke, brain tumor, encephalitis;
  • Pain, constipation, urinary retention;
  • Environment — sensory deprivation, sleep disruption (especially in ICU).

5. Clinical features

Three motor subtypes

• Hyperactive — agitation, hallucinations — diagnosis is easy;
• Hypoactive — sedation, withdrawal — frequently underdiagnosed, resembles depression.
• Mixed — fluctuation.

Clinical signs

• Acute onset (hours–days) and fluctuation.
• Attention impairment.
• Cognitive deficits — memory, orientation (time, place, person).
• Perceptual disturbances — visual hallucinations typical.
• Sleep-wake cycle disruption.
• Sundowning — worsening in evening hours.

6. Diagnosis

6.1 Unified diagnostic criteria

A. Attention impairment (focusing, maintenance, shifting) and consciousness impairment.

B. Disorder develops over a short period (hours–days); differs from baseline indicators; fluctuates within day.

C. Additional cognitive impairment (memory, orientation, language, visuospatial, perception).

D. Not fully explained by dementia or another neurocognitive disorder

E. Evidence from history, examination, and laboratory findings indicates that the disturbance is directly due to medical condition, substance intoxication/withdrawal, or multiple etiologies.

6.2 Differences between sources

• DSM-5-TR / ICD-11 — same.
• NICE CG103 — Delirium: prevention, diagnosis, management (2010, 2019 update).

6.3 Diagnostic algorithm

1. CAM (Confusion Assessment Method) — gold standard screening.
2. CAM-ICU — for the intensive care unit.
3. Medical cause investigation: complete blood count, electrolytes (Na, K, Ca, Mg, P), glucose, liver, kidney, TSH, B12, troponin, ECG, urine analysis and culture, blood culture, chest X-ray, brain MRI/CT, EEG (seizure suspicion), lumbar puncture (encephalitis/meningitis).
4. Medication list review — anticholinergics, opioids, benzodiazepines (Beers Criteria).
5. Toxicology.
6. Comorbid dementia assessment (initial indicators).

6.4 Differential diagnosis

7. Examination and assessment

• CAM, CAM-ICU.
• MMSE or MoCA (initial indicators of cognitive function).
• As in the medical workup above.
• EEG — rule out non-convulsive status.

8. Treatment

8.1 General principles (NICE CG103)

1. Etiological treatment is the first priority — correction of infection, metabolic disturbance, medication, and the hospitalization context.
2. Environmental modification — sensory (glasses, hearing aid), daylight, nighttime darkness, quiet environment, presence of loved ones.
3. Bedside care — hydration, nutrition, urination and defecation, movement.
4. Antipsychotic (haloperidol 0.25–2 mg, quetiapine, risperidone) — only for severe agitation or when the patient poses a danger to self/others, short-term, low dose. NICE CG103 — antipsychotics not routinely recommended; evidence base is limited (Burry L. Cochrane 2018).
5. Benzodiazepine — only in alcohol or benzodiazepine withdrawal delirium; otherwise is contraindicated (exacerbates delirium).
6. Prevention — ABCDEF bundle in ICU (Assess pain, Both SAT/SBT, Choice of sedation, Delirium, Early mobility, Family).

8.2 Treatment methods

1. Confusion Assessment Method (CAM — Confusion Assessment Method) — Inouye S.K. — 4 core features: acute onset/fluctuation + inattention + disorganized thinking or altered consciousness.
2. CAM-ICU — Adapted for intensive care; in patients on a ventilator.
3. Hospital Elder Life Program (HELP) — Inouye (Inouye S.K.) — Multicomponent delirium prevention program; evidence base strong.

8.3 Differences between sources

• NICE CG103 — etiological and environmental approach first-line; antipsychotics limited.
• SCCM PADIS Guidelines (for ICU, 2018).
• Burry L. Cochrane 2018 — antipsychotics do not reduce delirium duration or mortality.

9. Prognosis

• Hospital mortality 25–33%.
• In survivors — functional decline, long-term cognitive impairment, increased dementia risk.
• Early etiological intervention improves prognosis.

10. Myths and misconceptions

Myth 1: “Delirium is ‘normal for an elderly person’”

Evidence: Delirium is a clinical emergency with high mortality; it requires active intervention.

Myth 2: “Antipsychotics are a treatment for delirium”

Evidence: NICE CG103, Burry Cochrane 2018 — antipsychotics do not reduce delirium duration or mortality; only for severe agitation.

Myth 3: “Benzodiazepine is safe for an elderly agitated patient”

Evidence: benzodiazepines exacerbate delirium; only in the case of alcohol/BZ withdrawal.

Myth 4: “Hypoactive delirium is ‘good’ and requires no intervention”

Evidence: hypoactive delirium linked to worse mortality; problem of under-detection.

Myth 5: “Sleeping is best for the patient with delirium”

Evidence: Daytime activity, presence of close ones, sensory stimulation are recommended; HELP program is evidence-based.

11. Sources

1. WHO. ICD-11. 6D70 Delirium. 2024.
2. APA. DSM-5-TR. 2022.
3. NICE CG103. Delirium: prevention, diagnosis and management. 2010, 2019 update.
4. Inouye S.K. et al. Clarifying confusion: the confusion assessment method. Ann Intern Med 1990;113(12):941–948.
5. Burry L. et al. Antipsychotics for treatment of delirium in hospitalized non-ICU patients. Cochrane Database Syst Rev 2018;(6):CD005594.
6. Devlin J.W. et al. SCCM PADIS Guidelines. Crit Care Med 2018;46(9):e825–e873.