Dementia

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Dementia is a progressive cognitive disorder affecting memory, thinking, behaviour, and the ability to perform daily activities. It is caused by neurodegeneration or vascular damage.

Aetiology

1. Alzheimer’s Disease (Most Common - 60–80% of cases):

  • Accumulation of beta amyloid plaques and tau protein tangles leading to neuronal damage.

2. Vascular Dementia (Multi-infarct Dementia):

  • Due to multiple small strokes or chronic cerebral ischaemia.
  • More common in individuals with hypertension, diabetes, or cardiovascular disease.

3. Lewy Body Dementia:

  • Caused by abnormal deposits of alpha-synuclein (Lewy bodies) in the brain.
  • Features visual hallucinations, fluctuating cognition, and Parkinsonian features.

4. Frontotemporal Dementia (FTD):

  • Affects the frontal and temporal lobes.
  • Leads to personality changes, disinhibition, and loss of executive function.

5. Other Causes:

  • Normal pressure hydrocephalus.
  • Chronic alcohol use (Korsakoff syndrome).
  • Prion diseases (e.g., Creutzfeldt-Jakob disease).
  • Parkinson’s disease dementia.

Pathophysiology

  • Neurodegeneration leads to progressive loss of neurons and synapses.
  • Accumulation of toxic proteins (beta-amyloid, tau, alpha-synuclein) disrupts neuronal function.
  • Chronic ischaemia in vascular dementia results in white matter damage and cognitive decline.

Risk factors

  • Advancing age.
  • Family history of dementia.
  • Hypertension, diabetes, and hyperlipidaemia.
  • Smoking and excessive alcohol use.
  • Head trauma.
  • Low physical and cognitive activity.

Signs and symptoms

Early Symptoms:

  • Memory loss (short term memory affected first).
  • Difficulty finding words.
  • Impaired problem solving.
  • Disorientation (time, place, person).

Moderate to Severe Symptoms:

  • Loss of ability to perform daily activities.
  • Behavioural changes (aggression, apathy).
  • Hallucinations (common in Lewy body dementia).
  • Gait disturbances (vascular dementia, Parkinson’s dementia).

Investigations

  • Cognitive Assessment:
    • Mini Mental State Examination (MMSE).
    • Montreal Cognitive Assessment (MoCA), this is preferred for early dementia.
  • Blood tests:
    • Full blood count (rule out anaemia).
    • Thyroid function tests (rule out hypothyroidism).
    • Vitamin B12 and folate (rule out deficiency related cognitive impairment).
    • HbA1c, lipid profile (assess vascular risk factors).
  • Imaging:
    • CT or MRI brain (assess for strokes, atrophy, or hydrocephalus).
    • SPECT or PET scans (functional imaging in unclear cases).

Management

1. Lifestyle Modifications:

  • Encourage physical and cognitive activity.
  • Manage cardiovascular risk factors (hypertension, diabetes, cholesterol).
  • Healthy diet (Mediterranean diet shown to be protective).
  • Smoking cessation and alcohol moderation.

2. Pharmacological Management:

For Alzheimer’s Disease:

  • Acetylcholinesterase inhibitors: donepezil, rivastigmine, galantamine (used in mild-moderate disease).
  • NMDA receptor antagonist: memantine (used in moderate-severe cases).

For Vascular Dementia:

  • Optimisation of vascular risk factors (e.g., blood pressure, diabetes control).
  • Antiplatelets if indicated (e.g., aspirin or clopidogrel).

For Lewy Body Dementia:

  • Acetylcholinesterase inhibitors (e.g., rivastigmine).
  • AVOID typical antipsychotics as they worsen symptoms.

For Frontotemporal Dementia:

  • Currently no disease-modifying treatments; symptomatic management.

3. Psychological and Social Support:

  • Referral to memory clinics.
  • Support for carers (education, respite services).
  • Environmental modifications (e.g., fall prevention, labelling household items).
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