Synopsis
Recognise the cognitive, visual, sleep, motor and autonomic signature of dementia with Lewy bodies, use indicative investigations when uncertainty matters, and treat symptoms while avoiding severe antipsychotic sensitivity and compounding orthostatic or cognitive harm.
- Core clinical features are marked cognitive fluctuation, recurrent well-formed visual hallucinations, REM sleep behaviour disorder and spontaneous parkinsonism.
- Early cognition often emphasises attention, executive and visuoperceptual dysfunction; prominent storage-memory loss may be less striking than in typical Alzheimer disease.
- Fluctuation means spontaneous variation in attention and alertness over minutes, hours or days, not simply good and bad months or delirium during infection.
Key red flags
Disproportionate sedation, confusion, immobility, rigidity, swallowing decline or autonomic instability after an antipsychotic is a major warning and may require emergency treatment.
Investigation priorities
Establish fluctuation, hallucinations, dream enactment, parkinsonism and their temporal relationship to cognitive decline.
Management branches
Dementia presents with visual, fluctuation, motor or sleep features.
- 1. Obtain patient and collateral descriptions of hallucinations, short-timescale alertness variation, dream enactment and motor change, documenting onset relative to dementia.
- 2. Review antipsychotic, antiemetic, sedative and dopaminergic exposures and exclude delirium, eye disease, sleep apnoea and vascular mimics.
Key medicines
RivastigmineStart 1.5 mg orally twice daily with food and increase no more often than every two weeks towards the lowest helpful tolerated dose; a transdermal pathway may suit selected adherence or gastrointestinal problems.
Levodopa for disabling parkinsonismA specialist may begin a low levodopa combination dose, such as co-beneldopa 12.5/50 mg once to three times daily, and increase slowly against a defined mobility goal.