What is vascular dementia?

Vascular dementia, the second most common cause of dementia, accounts for slightly more than 20 percent of dementia cases. It is usually the result of damage that is done to the brain by a stroke, which happens when a blood clot or a hemorrhage cuts off the brain's blood supply.

Sometimes just a single stroke will cause the dementia. That type of case is called a single-infarct dementia. It is more common, however, for a number of small strokes to have the cumulative effect of destroying brain tissue and affecting memory, language and other cognitive functions. When this happens, it is described as multi-infarct dementia.

Vascular (or multi-infarct) dementia refers to a decline in a person's mental abilities that results from a series of strokes. A stroke occurs when blood flow to part of the brain is blocked, cutting off the blood supply to the brain.

Vascular dementia often progresses step by step, with declines in memory and mental functions occurring each time another stroke occurs. The specific symptoms a person has depend on which area of the brain the strokes have affected. Not all strokes cause symptoms.

Vascular dementia is often associated with hardening of the arteries (atherosclerosis) caused by high cholesterol, high blood pressure, or diabetes. A person can reduce the risk of future strokes by controlling high blood pressure, reducing cholesterol, quitting smoking, and taking aspirin and other drugs used to treat these conditions.

Vascular cognitive impairment refers to cognitive problems that stem from insufficient blood flow to portions of the brain. The decrease in blood flow is often the result of atherosclerosis (the accumulation of fatty deposits on artery walls) in the blood vessels that feed the brain. The resulting interruption of blood flow in small arteries creates areas of dead tissue. These events -- which are in fact tiny strokes -- often go unnoticed, because each one damages just a small part of the brain and may not cause obvious cognitive impairment. But the cumulative damage can lead eventually to large areas of dead brain tissue, and symptoms such as confusion, impaired thinking, slurred speech, problems with walking, and paralysis may arise. When severe, the condition is called vascular dementia.

Strokes in larger blood vessels can also cause dementia. People with vascular dementia usually have hypertension (high blood pressure), cardiovascular disease, diabetes, high cholesterol and triglycerides, or a history of stroke. The classic symptom of vascular dementia is an abrupt mental change, sometimes accompanied by paralysis or slurred speech. The mental deterioration proceeds in a "stairstep" pattern -- a person suffers a sudden cognitive decline, the decline levels off, and then new strokes cause more sudden declines.