Dementia with Lewy Body Disease

Background

  • A common cause of dementia (5-10% of cases).
  • Although it shares features of both alzheimer’s disease and parkinson’s disease, it is a seperate entity with a different course.

Clinical features

  • Dementia with relative sparing of short-term memory
  • Parkinsonism (bradykinesia, rigidity, tremor)
  • Cognitive decline- often fluctuating and may seem to improve and regress
  • Complex visual hallucinations (aliens/faces)
  • Often concomitant depression too.
  • Recurrent falls/syncope
  • Also, REM sleep disorder/restless leg syndrome

Investigations

  • DAT (dopamine) scan (SPECT)
  • (MIBG scan may also be useful)

Pathophysiology

  • Lewy bodies are eosinophilic intracytoplasmic neuronal inclusions of abnormally phosphorylated neurofilament proteins aggregated with ubiquitin and alpha-synuclein.  They seem to cause decreased ACh transmission in the brain.
  • Lewy neurites (ubiquitin and alpha-synuclein neuritic degeneration), Alzheimer’s change and vascular change may all be present too.

Management

  • Rivastigmine (anticholinesterase drug) may be beneficial
  • IMPORTANT- a feature of Lewy body dementia is the hypersensitivity to neuroleptic drugs. If there is suspicion about Lewy-body dementia, the patient must be closely monitored while these drugs are given.  Avoid neuroleptic treatment if possible.
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