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Delirium Superimposed on Dementia — MRCPsych Paper B MCQ

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ModerateOld Age PsychiatryDelirium Superimposed on DementiaMRCPsych Paper B

A 65-year-old woman with established vascular dementia is admitted from home. Her daughter reports that her cognition and everyday functioning had been stable for the previous 6 months. Over the past 24 hours, she has alternated between drowsiness and agitation, cannot sustain attention when asked to recite the months backwards, and reports seeing children in the room. She is febrile and has dysuria consistent with a urinary tract infection. Which diagnosis best accounts for her current presentation?

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Correct answer: D — Delirium superimposed on vascular dementia

The diagnosis is delirium superimposed on vascular dementia. The decisive features are the abrupt onset over 24 hours, fluctuation in arousal, impaired attention and perceptual disturbance, occurring against a previously stable dementia baseline with a likely infectious precipitant. NICE identifies recent fluctuating changes in cognition or perception as indicators of delirium and advises managing delirium first if distinction from dementia is difficult. Progression or behavioural and psychological symptoms of dementia would not usually produce this acute disturbance of attention and consciousness. Dementia with Lewy bodies can cause visual hallucinations and cognitive fluctuations, but these are generally recurrent or chronic and do not better explain the infection-associated acute change. Non-convulsive status epilepticus is a differential diagnosis but is less likely without supporting seizure features.

Reference: National Institute for Health and Care Excellence. Delirium: prevention, diagnosis and management in hospital and long-term care. CG103, recommendations 1.3.1, 1.6.1–1.6.3 and 1.7.1; updated 2023. https://www.nice.org.uk/guidance/cg103/chapter/Recommendations