Dementia

  • Definition
    • Diminution of cognition in clear consciousness
    • Decrement of 2 or more intellectual functions
    • Impairment of short and long term memory
  • Changes of Dementia involve
    • Cognition
    • Memory
    • Language
    • Visuospatial
  • Behavioural disturbance involve
    • Restlessness
    • Wandering
    • Violence
    • Delusions
    • Social & Sexual disinhibition

Types of dementia

  • Alzheimer’s
    • Global
  • Vascular
  • Pick’s disease
    • Frontal
  • Lewy body
    • Parkinson’s
  • Huntington’s
  • CJD
  • Kuru

Aetiology

  • Parenchymal/degenerative
    • Alzheimer’s disease
    • Pick’s Disease
  • Intracranial Tumour
    • Head Trauma
    • Subdural  Haematoma
  • Infection
    • Neurosyphilis
    • TB
    • SSPE
  • Endocrine
    • Hypothyroidism
    • hyperparathyroidism
  • Metabolic  Uraemia
    • Hypoglycaemia
    • calcium imbalance
  • Vitamin Deficiency
    • Folate
    • Pellagra (Niacin)
  • Toxins
    • Heavy Metal Poisoning
    • Prolonged alcohol misuse

Pathophysiology

  • Fronto-temporal
    • Disease
      • Pick’s disease (20%)
      • NPH & MND (70%)
    • Characterised by
      • prominent ‘personality change’
    • May manifest as a ‘frontal  lobe syndrome’
    • Early –onset dementia is often undiagnosed
    • Language impairments tend to involve reduction in content
      • semantic  anomia
      • tend to replace words with something else
      • eg. dog = cat , fruits, vegetables, names
    • CT shows
      • fronto –temporal atrophy
    • SPECT shows
      • FT metabolism
    • Neuropathology (Pick’s disease)
      • Intraneuronal inclusion bodies
      • Demyelination and gliosis of frontal lobe
        • Gliosis: proliferation of astrocytes in damaged areas of the CNS. Leads to formation of glial scars
  • Temporo-parietal
    • Disease
      • Alzheimer’s Disease
    • Characterised by
      • early memory loss
      • Focal Cognitive Deficits
      • Personality Changes
        • are later manifestations
      • Problem with word–finding
        • lexical anomia
        • cannot find the word to say
    • CT shows
      • thinning of cortex
    • Neuropathology
      • Amyloid plaques
      • Neurofibrillary tangles
      • 50% loss of neurons in the cortex and hippocampus
      • Degeneration of cholinergic neurons in basal forebrain
  • Subcortical
    • Disease
      • Parkinson’s disease
      • Huntington’s disease
      • Wilson’s disease
      • Binswanger  Encephalopathy
      • HIV-related dementia
    • Clinical Features
      • Gross Psychomotor
      • Slowing Depressed Mood
      • Movement Disorders
      • Mild amnesia 
      • Personality Changes
    • Neuropathology
      • Involves
        • brainstem
        • cerebellum
        • basal ganglia
      • Gliosis and cell loss of the above structures
        • Gliosis: proliferation of astrocytes in damaged areas of CNS. Leads to formation of glial scars
      • Preservation of cortex
      • Calcification

Neuropsychiatric features

  • Depending on the type of dementia
  • Alzheimer’s
    • aphasia
      • speech disorder
    • apraxia
      • loss of ability to do purposeful movemet
    • agnosia
      • loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss
    • abnormal executive functioning
  • Vascular
    • same as above
    • but stepwise deterioration
      • with evidence of vascular event
  • Frontal
    • disinhibition
    • disrupted eating behavior
    • sensory agnosia
    • hyperorality
  • Subcortical
    • gait disturbance
    • dysarthria
      • motor speech disorder, poor articulation
    • dystonic movements
      • neurologic movement disorder characterized by sustained muscle contractions, usually producing twisting and repetitive movements or abnormal postures or positions

Investigations

  • Mini mental state
  • Wisconsin card sorting test
  • Digit learning test
  • Test of verbal ability
  • Test for non verbal ability
  • Neuroimaging

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