Persistent Delirium

Persistent delirium is delirium that does not resolve within the expected time, remaining after the precipitating illness has been treated and continuing for weeks to months, often beyond hospital discharge.

A substantial minority of older patients still have delirium at discharge, and some at 1 to 3 months. The risk is highest with dementia, frailty, hypoactive subtype and long, severe episodes.

Pathophysiology. Ongoing neuroinflammation, cholinergic deficiency, neuronal injury and underlying neurodegeneration may prevent recovery of network function. Unrecognised precipitants, drug effects and poor sleep sustain the state.

Continuing inattention, disorientation, fluctuating alertness, sleep disturbance, hallucinations or withdrawal, and slow functional recovery. Prolonged delirium often leaves new cognitive decline, dependence and a risk of care home admission and death.

Repeat the search for causes: drug review (especially anticholinergics, sedatives and opioids), occult infection, metabolic and endocrine disturbance (thyroid, vitamin B12, folate, thiamine, calcium), urinary retention, constipation, pain, sleep apnoea, alcohol and sensory loss. Image the brain (subdural haematoma, stroke, hydrocephalus) and consider EEG and lumbar puncture when no cause is found. Reassess cognition after 4 to 6 weeks to separate dementia from delirium.

Differential diagnosis.

• Undiagnosed dementia.
• Depression, non-convulsive status epilepticus and autoimmune encephalitis.
• Chronic subdural haematoma and normal pressure hydrocephalus.

Continue treating all contributors. Discontinue deliriogenic drugs, restore sleep, hearing and vision, mobilise, and maintain nutrition and hydration. Use antipsychotics only for severe distress, at the lowest dose and for the shortest time. Plan discharge with family and community teams, and arrange cognitive review and rehabilitation.

Monitoring. Cognition and function at 4 to 6 weeks and 3 months.

Referral and escalation. Refer to a geriatrician, old age psychiatrist or neurologist when delirium persists after several weeks.