Delirium

Overview

Delirium is a syndrome of acute brain dysfunction. The defining problem is not simply poor memory: attention and awareness change abruptly and fluctuate during the day. A person may be lucid in the morning and markedly confused at night, or alternate between agitation and somnolence. Because delirium reflects an underlying disturbance, the diagnostic question is “what caused the brain to fail now?” ^{[1] [2]}

Older adults, people with dementia, frailty, sensory impairment or severe illness are particularly vulnerable, but delirium can occur at any age. Hospitalization, surgery and intensive care are common settings. It is often multifactorial—for example, infection plus dehydration plus a sedating medicine rather than one single cause. ^{[1] [3]}

Symptoms and warning signs

Symptoms include new disorientation, inability to focus, disorganized thinking, altered alertness, reversed sleep–wake cycle, perceptual disturbances, hallucinations or emotional changes. Hyperactive delirium is obvious when a person is restless or pulling at lines, but hypoactive delirium may present as quiet withdrawal, slowed responses and excessive sleepiness and can be more easily missed. ^{[1] [2]}

Diagnosis

Diagnosis is clinical. Clinicians establish the person’s baseline cognition, determine whether the change began acutely and fluctuates, and test attention and thinking. Family, caregivers or nursing staff often provide the most important timeline. Structured tools such as the Confusion Assessment Method can support bedside recognition but do not replace clinical evaluation. ^{[1] [3]}

The cause-focused work-up is individualized and may include blood glucose, oxygen saturation, blood count, electrolytes, kidney/liver tests, urinalysis or cultures, medication review and targeted imaging. CT or MRI is not automatic for every delirium but becomes important with head injury, focal neurologic signs, seizure or another structural concern. ^{[1] [2]}

Common causes and triggers

Frequent causes include infection, dehydration, electrolyte disturbance, hypoxia, kidney or liver failure, medication effects, pain, urinary retention, constipation, surgery/anesthesia and alcohol or sedative withdrawal. In older adults, a relatively modest physiologic disturbance may trigger delirium when baseline brain vulnerability is high. ^{[1] [2]}

Delirium and dementia can coexist

Dementia is a major risk factor for delirium, so an existing dementia diagnosis should not be used to explain away a sudden change. A person with stable chronic cognitive impairment who becomes abruptly more confused, sleepy, agitated or inattentive should be assessed for delirium and a new medical trigger. Recovery can be slower in people with underlying dementia. ^{[2] [3]}

Treatment and management

The main treatment is to identify and reverse the cause: treat infection, correct oxygen or glucose problems, restore appropriate hydration, relieve pain, address urinary retention or constipation, and stop or reduce contributing medicines when safe. The care environment should also support orientation with clocks and familiar people, preserve day–night cues, promote mobility, and ensure glasses and hearing aids are available. ^{[1] [3]}

Routine sedative treatment is generally avoided because it can worsen delirium and falls. Antipsychotic medication may be used for a short time in selected patients with severe agitation or distress that threatens safety after non-drug measures fail, but it does not treat the underlying delirium and carries important risks. Alcohol or benzodiazepine withdrawal is a special case where sedative medication is part of cause-specific treatment. ^{[2] [3]}

Recovery and prognosis

Delirium is often reversible, but recovery can take days to weeks and some older or critically ill patients have persistent cognitive or functional decline after the acute trigger resolves. Delirium is associated with longer hospital stays and greater risk of complications, so follow-up should review cognition, function, medicines and the condition that caused the episode. ^{[2] [3]}

Preventing delirium in hospital

Multicomponent prevention focuses on orientation, sleep, early mobility, hydration, adequate pain control, medication review, sensory aids and avoiding unnecessary catheters or restraints. No single drug has replaced these basic measures as the standard prevention strategy for at-risk hospitalized adults. ^[3]

Sources

1. MedlinePlus — Delirium
2. MedlinePlus Medical Encyclopedia — Delirium
3. JAMA / PMC — Delirium in Older Persons: Advances in Diagnosis and Treatment
4. NICE — Delirium: prevention, diagnosis and management (CG103)

This article is based on trusted medical sources and is awaiting clinician review. It is not a substitute for personalized medical advice.