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DLB — MRCPsych Paper B MCQ

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ModerateOld Age PsychiatryDLBMRCPsych Paper B

A 76-year-old man has an 18-month history of progressive cognitive decline that now interferes with managing his medication and finances. His attention and alertness vary markedly during the day. He repeatedly sees detailed images of unfamiliar children in the house and has begun acting out vivid dreams. Examination shows bradykinesia and limb rigidity, which developed after the onset of cognitive symptoms. What is the most likely diagnosis?

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Correct answer: A — Dementia with Lewy bodies

The correct answer is dementia with Lewy bodies. The patient has functional cognitive decline together with all four core clinical features: pronounced cognitive fluctuations, recurrent well-formed visual hallucinations, REM sleep behaviour disorder and spontaneous parkinsonism. Two or more core features support probable DLB. Alzheimer's disease more typically presents with prominent episodic memory impairment and does not usually produce this clustered phenotype early. Vascular dementia is suggested by a temporal relationship to cerebrovascular disease, stepwise decline or focal neurological findings. Frontotemporal dementia usually presents with early behavioural disinhibition, apathy or language dysfunction. Normal-pressure hydrocephalus causes a predominantly gait-first syndrome with urinary dysfunction and cognitive impairment, rather than formed hallucinations, dream enactment and fluctuating alertness.

Reference: McKeith IG et al. Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium, core clinical features, 2017. https://pubmed.ncbi.nlm.nih.gov/28592453/