Final answer:
Vascular dementia is caused by insufficient blood flow and oxygen to the brain, typically resulting from blocked or narrowed blood vessels. An ischemic stroke is a common cause of this type of dementia, leading to neurological deficits due to cell death.
Step-by-step explanation:
Vascular dementia is caused when the brain is deprived of oxygen or nutrients. This type of dementia can result from narrowing or blockage of blood vessels, leading to insufficient blood flow (ischemia) and oxygen to the brain. The term for loss of blood flow to the brain, causing cell death, is known as a stroke or a cerebrovascular accident (CVA).
There are two main types of strokes: ischemic and hemorrhagic. An ischemic stroke, which accounts for almost 90 percent of all strokes, is often caused by an embolus, such as a blood clot or fat deposit that blocks a blood vessel. Vessels can also be narrowed by thickening of their walls, leading to reduced blood flow (ischemia) and oxygen (hypoxia) to brain tissue, which in turn can lead to cell death and significant neurological deficits.
Therefore, the answer to the question is (a) Vascular. Vascular dementia is directly related to problems with blood circulation to the brain, and can significantly impair cognitive function due to the death of brain cells.