Which form of dementia is caused by repeated infarcts or obstructions of blood vessels that prevent sufficient blood from reaching the brain?

• A. Amyloid plaques only
• B. Neurofibrillary tangles alone
• C. Lewy bodies
• D. Repeated infarcts obstructing blood flow

Answer: (D)

The key idea is vascular dementia, which occurs when repeated strokes or blockages in brain blood vessels reduce blood flow enough to cause brain tissue damage. Each infarct damages a patch of brain, and as more occur, cognitive abilities decline in a stepwise fashion, often with accompanying focal neurological signs. This mechanism is different from Alzheimer’s disease, where the hallmark changes are amyloid plaques and neurofibrillary tangles, and from Lewy body dementia, where Lewy bodies are central. So the description of repeated infarcts obstructing blood flow best fits vascular dementia.