7.5.5 Delirium in later life

The delirium syndrome

• Delirium is an acute change in attention and awareness. It develops over hours to days from the person's normal baseline and fluctuates within the day.

• Its hallmark is impaired consciousness: disturbed attention and reduced awareness of the surroundings, also called clouding of consciousness.

• Memory, language and perceptual disturbances support the diagnosis but are not required.

• Disturbance of the sleep-wake cycle is the most consistently present feature, found in nearly all cases and more often than psychotic, motor or affective features.

• In ICD-11, delirium causes global cognitive impairment across several domains at once, including visuospatial function, with fluctuation, emotional change and reduced arousal, rather than a deficit confined to one domain.

• ICD-11 requires a physiological cause, such as illness, medication, intoxication or withdrawal, and several causes often act together.

Motor subtypes

New drowsiness, withdrawal or reduced intake deserves the same attention as agitation.

How common delirium is

Prevalence rises steeply with severity of illness and with care setting, and exceeds 80% in the sickest groups.

Causes: vulnerability and precipitant

The greater the baseline vulnerability, the smaller the insult needed to trigger delirium.

• Drugs with marked central anticholinergic (antimuscarinic) activity that cross the blood-brain barrier are among the commonest precipitants in older adults, and they can be changed.

• Clinicians should not stop at the first plausible cause, because infection often coexists with retention, pain, dehydration and drug toxicity.

• A positive urine dipstick does not establish urinary infection in people over 65, because asymptomatic bacteriuria is common.

Separating delirium from its mimics

Acute onset from a normal baseline, fluctuating attention and awareness, and a physical precipitant mark out delirium.

Tap to enlarge

In established dementia, sudden deterioration usually signals an added problem, so compare the current state with carers' account of usual cognition.

Bedside assessment

• The 4AT tests alertness, orientation (age, date of birth, place, year), months backwards, and acute change or fluctuation, takes under two minutes, and is the tool the National Institute for Health and Care Excellence (NICE) prefers outside critical care.

• A 4AT score of 4 or more suggests possible delirium, 1 to 3 suggests possible cognitive impairment, and 0 does not exclude delirium.

• The Confusion Assessment Method (CAM) needs acute or fluctuating change and inattention, plus disorganised thinking or altered consciousness; its CAM-ICU version is used in critical care.

Prevention

• About 30 to 40 per cent (roughly a third) of delirium arising in hospital is preventable, because modifiable ward factors drive a substantial minority of cases.

• NICE CG103 recommends multicomponent non-drug care: orientation and familiar people, mobility, hearing aids and glasses, sleep, hydration, nutrition, pain control, medication review, and avoiding unnecessary catheters and restraint.

• In a placebo-controlled trial in older adults having hip surgery, prophylactic haloperidol did not change the incidence of postoperative delirium but reduced its severity and duration.

Management

• Treat the causes, and use calm explanation, consistent staff and family involvement; antipsychotics do not reliably shorten delirium.

• NICE advises considering short-term, low-dose haloperidol for distress or risk only once verbal and non-verbal de-escalation has failed or is inappropriate, usually for one week or less.

• Haloperidol is the conventional first choice in older inpatients because it has almost no anticholinergic activity.

• Before haloperidol, obtain a baseline ECG and correct electrolytes, then monitor for cardiac effects, postural hypotension, extrapyramidal symptoms and swallowing problems, reviewing daily.

• Haloperidol is contraindicated in Parkinson's disease and dementia with Lewy bodies, where specialist advice is needed; quetiapine also carries risk.

• Benzodiazepines are not recommended outside alcohol or sedative withdrawal, because they lack evidence and worsen confusion.

• In palliative care, delirium does not respond dependably to antipsychotics, which may deepen clouding of consciousness.

Course and outcomes

• Delirium is associated with falls, functional decline, institutionalisation, higher mortality and later cognitive decline, but not every patient develops dementia.

• The discharge summary should record the episode, its causes and remaining symptoms, with reassessment once the patient is medically stable.