Vascular dementia: stepwise decline
Vascular dementia usually declines in steps: the person is stable for a period, then drops suddenly after a stroke or other event in the brain's blood supply.
Remember
Sudden drops after strokes, with stable periods between, point to vascular dementia; a smooth, continuous decline points to Alzheimer's disease, the dementia led by early loss of recent memory.
Memory aid
vascular dementia is a staircase, Alzheimer's disease is a slope
Think of vascular dementia as steps with level stretches between drops, and Alzheimer's disease as a smooth slope.
Vascular dementia is the second most common dementia in people over 65. It follows cerebrovascular events (problems with the blood supply to the brain), such as strokes and repeated transient ischaemic attacks (brief stroke-like episodes that recover).
The course is usually stepwise: the patient is stable for a period, then undergoes a steep decline after an event. Each stroke damages a patch of brain, because a blood vessel is blocked or leaks. An infarct (an area of tissue death from lost blood supply) kills neurones permanently, so function is lost in steps and the losses add up over time.
By contrast, in Alzheimer's disease neurones are lost steadily, so the decline is smooth and starts with recent memory.
Risk factors include a history of stroke, hypertension, high cholesterol, diabetes and smoking. Depending on the brain area affected, there may also be focal neurological signs (signs from one part of the brain, such as weakness or speech difficulty). Executive dysfunction (trouble with planning, organising and problem solving) is common when frontal and deep white matter pathways are injured.
Vascular dementia can often be found alongside Alzheimer's disease, which is known as mixed dementia.
Key facts
- Course
- usually stepwise, with stable periods and then sudden drops after cerebrovascular events
- Cause
- cerebrovascular events such as strokes and repeated transient ischaemic attacks
- Mechanism
- every infarct kills neurones permanently, so the losses add up over time
- Risk factors
- history of stroke, hypertension, high cholesterol, diabetes and smoking
- Examination
- focal neurological signs may be present, and executive dysfunction is common when frontal and deep white matter pathways are injured
- Contrast
- Alzheimer's disease declines smoothly and continuously
Exam traps
- Early, prominent loss of recent memory with a smooth, continuous decline is the usual picture of Alzheimer's disease, so it does not point to vascular dementia.
- Beta-amyloid plaques are a hallmark of Alzheimer's disease and cause slowly progressive neuronal failure, so they do not explain abrupt drops in function.
- Visual hallucinations (seeing people or animals that are not there) with fluctuating attention suggest dementia with Lewy bodies, a different condition, rather than vascular dementia.
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