Psychiatry - Dementia With Lewy Bodies Flashcards
Dementia with Lewy Bodies
Dementia with Lewy bodies (DLB) is the second most common cause of dementia in the elderly after Alzheimer’s disease:
- Progressive dementia, however other features are characteristic:
- Parkinsonism often accompanies, or even precedes, the dementia
- the level of cognitive impairment fluctuates from hour to hour and day to day
- complex visual hallucinations are common
- the patient is very sensitive to neuroleptic medication
Dementia with Lewy Bodies
Clinical Features?
The clinical features of dementia with Lewy bodies include:
- progressive decline in cognitive function, although this is often not the presenting complaint
- fluctuations in cognition, alertness and attention
- transient losses of consciousness
psychiatric features:
- visual hallucinations; less frequently other modalities may be involved
- complex, systematised delusions
- depression
spontaneous parkinsonism:
- rigidity
- bradykinesia
- tremor
- shuffling gait
hypersensivity to neuroleptic medication
repeated falls
Dementia with Lewy Bodies
Investigations?
Blood tests:
- FBC, ESR, CRP - anaemia, vasculitis
- T4 and TSH - hypothyroidism
- biochemical screen - hypercalcium or hypocalcaemia
- urea and creatinine - renal failure, dialysis dementia
- glucose
- B12 and folate - vitamin deficiency dementia
- clotting and albumin - liver function
Other possible blood tests include:
- syphilis serology
- HIV - if in young person
- caeruloplasmin - Wilson’s disease
- CSF for Creutzfeld-Jacob
- EEG
- Delirium, frontotemporal dementia
- Seizures
Imaging:
- imaging may help to identify treatable causes such as subdural haematoma, normal pressure hydrocephalus, cerebral tumours
- prefer MRI to assist with early diagnosis and detect subcortical vascular changes. However, CT scanning could be used
- priority for CT scan should be given to the following
- atypical presentation
- rapid unexplained deterioration
- unexplained focal neurological signs or symptoms
- history of recent head injury
- urinary incontinence
- gait ataxia early in the illness
Dementia with Lewy Bodies
Diagnostic Criteria?
Diagnostic criteria for dementia with Lewy bodies (BLB) are:
There must be a progressive cognitive decline
two of the following must be present:
- marked fluctuations in attention and alertness
- recurrent visual hallucinations
- parkinsonism
Features which support a diagnosis of DLB include:
- recurrent falls
- transient losses of consciousness
- neuroleptic sensitivity
- complex delusions
- hallucinations in modalities other than vision
Dementia with Lewy Bodies
Management?
Psychosis is often the most troublesome problem when managing a patient with dementia with Lewy bodies (DLB). Most patients are intolerant of the usual antipsychotics because of exquisite sensitivity to the side effects of these drugs. Antidepressants and small doses of benzodiazepines may be tried but are often of little benefit.
- The mainstay of management is ensuring that the environment is as safe and non-threatening as possible. Carers should be supported and motivated.
- There is some evidence that the acetylcholinesterase drugs such as rivastigmine may be beneficial in DLB, although this is not currently a licensed indication
- NICE have stated clinicians should consider an acetylcholinesterase inhibitor for people with DLB who have non-cognitive symptoms causing significant distress or leading to behaviour that challenges
Dementia with Lewy Bodies
What is a Lewy Body?
A Lewy body is a neuronal inclusion body which is seen:
- in the substantia nigra in patients with idiopathic Parkinson’s disease
- throughout the cortex in patients with dementia with Lewy bodies
- throughout the cortex in a subset who have a primary diagnosis of Alzheimer’s disease
Inclusion bodies are typically aggregated protein, in the case of the Lewy body the major component is alpha-synuclein.
