Vascular Dementia (VaD), also called multi-infarct dementia, occurs when the cells in the brain are deprived of oxygen. A network of blood vessels called the vascular system supplies the brain with oxygen. If there is a blood flow interruption in the vascular system, or if it is diseased, blood is prevented from reaching some parts of the brain. As a result, cells in the affected region of the brain die, leading to the symptoms of dementia.