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Dementia with Lewy Bodies

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Overview

Dementia with Lewy bodies (DLB) is the third most common type of dementia characterised by a progressive cognitive decline that is significant enough to affect a person’s ability to carry out activities of daily living.

DLB shares features with Alzheimer’s disease and Parkinson’s disease.

Pathophysiology

DLB is a synucleinopathy, which describes abnormal deposits of alpha-synuclein in the brain. Other synucleinopathies include Parkinson’s disease and Parkinson-plus syndromes (such as multiple system atrophy), explaining their close relationship.

Many patients with Alzheimer’s disease have Lewy bodies, giving rise to controversies about naming DLB.

Epidemiology

  • The third most common type of dementia
  • Prevalence increases with age 

Risk Factors & Associations

  • Older age
  • Family history

Presentation

Dementia is the main presenting feature. Early impairments in attention and executive function are seen as opposed to memory loss alone.

  • Cognition characteristically fluctuates
    • For example, swings between being alert, confused, or drowsy. This can occur over minutes to hours. 
  • Well-formed and (typically) visual hallucinations which are seen early in the disease
  • Features of Parkinsonism:
    • Tremor
    • Rigidity
    • Akinesia/bradykinesia
    • Postural instability
  • Falls
  • REM sleep disorders
  • Fainting spells

Differential Diagnoses

Parkinson’s disease

  • There is considerable overlap
  • In Parkinson’s disease, the motor symptoms may come first before cognitive symptoms

Alzheimer’s disease

  • No fluctuations in consciousness
  • No significant motor symptoms early in the disease
  • REM disorder not present

Vascular dementia

  • Cardiovascular history may be present
  • Cognitive and functional decline is in a stepwise manner

Frontotemporal dementia

  • Onset usually in the 50s, and more rapidly progressing
  • Impulsive and socially inappropriate behaviour
  • Personality changes are seen

Assessment

Screening tools

Cognitive assessment tools in a non-specialist setting include:

  • 10-point Cognitive Screener (10-CS)
  • 6-item Cognitive Impairment Test (6-CIT)
  • 6-item Screener
  • Memory Impairment Screen (MIS)
  • Mini-Cog
  • Test Your Memory (TYM)

Dementia should not be ruled out solely based on a normal cognitive assessment test.

Investigations

Initial investigations in primary care

Initial investigations are to rule out possible reversible causes of symptoms:

Other investigations may need to be considered if appropriate:

  • Chest x-ray
  • ECG
  • Urine microscopy and culture
  • Urine toxicology panel for opiates, cocaine, benzodiazepine and cannabinoids
  • Syphilis serology
  • HIV testing

Referral to secondary care

If the person is severely disturbed, arrange admission to hospital. Detention under the Mental Health Act (1983) may be needed.

If dementia is suspected in people with learning disabilities arrange a specialist referral for assessment and treatment.

People with MCI are followed up regularly and referred to secondary care if their symptoms deteriorate.

All other patients should be referred to a memory assessment service for specialist assessment and management.

Investigations in secondary care

Specialist investigations involve neuroimaging to screen for reversible structural causes (e.g. subdural haematoma). These may include:

  • MRI head
  • CT head

Other specialist tests are performed to help diagnose a dementia subtype and know more about the dementia subtype and adjust management:

  • Single-photon emission computed tomography (SPECT):
    • Also known as a DaTscan
    • Identifies low basal ganglia dopamine transporter uptake

Management

Overview

Acetylcholinesterase inhibitors may be used. Options are:

  • Donepezil
  • Rivastigmine
  • Galantamine

Patients that have acute behavioural disturbances e.g. severe anxiety may be managed with IM lorazepam.

For psychotic symptoms, neuroleptics should be avoided. Atypical antipsychotics are used with extreme caution and monitoring e.g. risperidone, olanzapine, and quetiapine.

  • Both atypical and typical antipsychotics must be used with caution as they can worsen Parkinsonism.
  • Typical antipsychotics are avoided

Monitoring

  • Monitoring is on a case-by-case basis. Often, patients are followed up every 6 months to look for functional or cognitive declines. Home safety risks should also be assessed at these visits.

Patient Advice

  • Discussions regarding future care i.e. lasting power of attorney, advance decisions, place of death, and wills should take place with the patient and their family and carers at an early stage.
  • Patients should stop smoking, reduce alcohol consumption, and eat a healthy balanced diet to reduce the risk of dementia or further decline, and to reduce the risk of frailty
  • When communicating with patients, family and carers etc. should use short and simple sentences and provide response choices to avoid confusion
  • Coping techniques should also be discussed with family and carers etc. of the patient.
  • Legal information surrounding driving should be given.

Complications

Prognosis

  • There is no cure
  • Dementia with Lewy bodies is progressive and shortens the lifespan
  • Average survival is around 5-8 years

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