Dementia

Neurocognitive disorder characteerised by progressive loss of cognitive function exceeding normal age-related decline across multiple domains, including:

Epidemiology and Risk Factors

Prevalence:

  • Highly prevalent, especially in aging populations

Incidence:

  • Doubles with every 5 year ↑ in age

Pathophysiology

Aetiology

Multiple potential aetiologies (which can be mixed), including:

  • Alzheimer’s disease
    Build up of β-amyloid plaques and τ neurofibrillary tangles causing neurone death. Impairments classically involve:
    • Memory
    • Language
    • Visuospatial
    • Orientation
    • Concentration
  • Vascular dementia
    Neuronal ischaemia due to stroke or multiple small subcortical infarcts. Impairments classically involve:
    • Planning and organisation
    • Memory
      Later feature compared with Alzheimer’s.
  • Lewy body dementia
    α-synuclein deposits within neurones. Impairments classically involve:
    • Cognitive impairment
      Similar or before motor symptoms.
    • Visual hallucinations
    • Parkinsonian signs
    • Fluctuating attention
  • Parkinson’s Dementia
    Lewy bodies.
    • Pre-existing Parkinson’s disease
    • Broad range of deficits
  • Frontotemporal dementia
    Genetic predisposition, leading to τ aggregation in frontal and temporal lobes. Impairments classically involve:
    • Behaviour
      • Lack of empathy
      • Disinhibition
    • Non-fluent aphasia
    • Semantic types
    • Younger
  • HIV-associated
    Direct viral damage. Impairments classically involve:
    • Short-term memory
    • Learning
    • Olfaction

Clinical Manifestations

Diagnostic Approach and DDx

Investigations

Management

Medical

Surgical

Anaesthetic Considerations

  • D
    • Capacity
    • Analgesia
      • Complex pain assessment
        Simplified scales helpful.
      • Consider empirical trial of analgesia if pain is a potential cause of behaviour/distress
      • ↓ reported pain but pain experience may be unchanged
    • Post-operative cognitive dysfunction
      • Consider using:
        • ERAS protocols
        • Dexmedetomidine
          May reduce POCD in high-risk patients.
      • Avoid:
        • Benzodiazepines
        • Opioid analgesics
          Insofar as is practicable.
        • Anticholinergics
          • Cyclizine
      • Behavioural control strategies
        • Non-pharmacological
          • Orientation
          • Family support
          • Sensory needs
            Glasses, hearing aids.
        • Pharmacological
          • Haloperidol 0.5-1mg PO/IM
          • Risperidone 0.25mg PO Avoid in PD or Lewy body dementia.
          • Olanzapine 2.5-5mg PO
            Avoid in PD or Lewy body dementia.
  • E
    • Acetylcholinesterase inhibitors
      • Prolong depolarising blockade
      • Inhibit or reverse non-depolarising blockade
      • Consider ceasing:
        • Donepezil requires a 2-3 week washout
        • Galantamine and rivastigmine can be ceased 1 day prior
          Ideally cease pre-operatively.
      • Sugammadex may be helpful if reliable offset required

Marginal and Ineffective Therapies

Complications

Prognosis

Key Studies

References