A 74-year-old man presents having suffered an episode of left arm and leg weakness that resolved after a few hours. His relatives have noticed that he has suddenly become very forgetful over the past week and is forgetting the names of people and places and having difficulty finding words for things.

1. What is the most likely cause of his cognitive decline?
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This patient appears to have suffered a recent transient ischaemic attack (TIA), and has a history consistent with a diagnosis of vascular dementia.

Vascular dementia is the second leading cause of dementia, accounting for around 25% of all cases. It involves damage to the brain caused by a variety of different mechanisms, including major strokes, multiple smaller unrecognised strokes (multi-infarct) or chronic changes in smaller vessels (subcortical dementia). Increasingly the term vascular cognitive impairment (VCI) is used to encompass this spectrum of disease.

2. What is the main differential diagnosis in this case?
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Alzheimer’s disease is the most common cause of dementia, accounting for around 50% of all cases, and is the main differential diagnosis in this case.

3. How can the diagnosis in this case be distinguished from differential diagnosis above?
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In contrast to Alzheimer’s disease, which is characterised by a slow and insidious onset, vascular dementia can occur suddenly and typically has a series of stepwise increases in symptom severity. The presentation can vary significantly, though, as can the speed of progression.

Features that are more suggestive of a vascular cause of dementia include:

  • History of TIAs or cardiovascular disease
  • Presence of focal neurological abnormalities
  • Prominent memory impairment in the early stages of disease
  • Early presence of disturbance in gait and unsteadiness
  • Frequent, unprovoked falls in early stages
  • Bladder symptoms (e.g. incontinence) without a demonstrable urological condition in early stages
  • Seizures

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