Inadequate blood flow can damage and eventually kill cells anywhere in the body. The brain has one of the body's richest networks of blood vessels and is especially vulnerable.

In vascular dementia, changes in thinking skills sometimes occur suddenly following strokes that block major brain blood vessels. Thinking problems also may begin as mild changes that worsen gradually as a result of multiple minor strokes or other conditions that affect smaller blood vessels, leading to cumulative damage. A growing number of experts prefer the term "vascular cognitive impairment (VCI)" to "vascular dementia" because they feel it better expresses the concept that vascular thinking changes can range from mild to severe.