Medical Edge Newspaper Column

Vascular Cognitive Impairment — A Potentially Preventable Cause of Dementia

February 20, 2009
Dear Mayo Clinic:
Is it true that there is a type of dementia that can be prevented? How is this different from Alzheimer's disease?

Answer:
Dementia is defined as a significant loss of intellectual abilities, such as memory, which is severe enough to interfere with day-to-day functioning. Fears about dementia often focus on one condition, Alzheimer's disease, which is the most common cause of dementia in older adults. Yet many people know little or nothing about vascular cognitive impairment (VCI), the second most common cause of dementia.

VCI, sometimes known as vascular dementia, can be mistaken for Alzheimer's disease. Alzheimer's disease accounts for about 75 percent of all dementia in Americans age 65 and older. Experts estimate that four million people in the United States are currently living with Alzheimer's disease, and that 1 in 10 people over the age of 65 and nearly half of those over the age of 85 have it.

VCI accounts for 10 to 20 percent of all dementias in older adults and occurs in 1 to 4 percent of all Americans over the age of 65.

VCI can be mistaken for Alzheimer's disease because both cause confusion and problems with memory, language, and calculations. The two diseases can occur together. However, the causes are quite different.

With Alzheimer's disease, for unknown reasons, plaques and tangles form in brain cells which interfere with normal brain function and eventually cause irreparable damage to the brain cells. VCI is caused by multiple small strokes (infarctions) which can occur when there is narrowing or complete blockage of arteries leading to or within the brain. Numerous small strokes cause multiple areas of brain damage over time. Even if the infarcts are "small" — meaning they don't cause any major stroke symptoms — they can gradually create enough damage to cause dementia.

Multiple strokes do not always cause dementia. In some cases, a single stroke can result in the sudden onset of dementia. This usually occurs when a stroke affects a critical area of the brain or if there has been prior, unrecognized brain damage from a different cause (e.g., head trauma).

VCI is caused by narrowing of large or small blood vessels which serve the brain. Risk factors for the development of arterial narrowing include high blood pressure (hypertension), smoking, high cholesterol, age, and diabetes. Profoundly low pressure (hypotension) and bleeding into the brain can lead to VCI as well.

With VCI, symptoms often begin suddenly and worsen in a stepwise fashion. However, VCI symptoms can develop gradually and thus can easily be confused with Alzheimer's disease. Common manifestations include confusion and agitation; problems with speech, language, and memory; unsteadiness when walking and frequent falls; loss of bowel and bladder control; and personality and mood changes.

One of the first symptoms of VCI often involves a decline in the ability to organize thoughts or actions. This makes it difficult to keep track of more than one thing at a time or to communicate details in a logical manner. Memory problems typically develop much later in VCI, which is different than Alzheimer's disease, where memory problems usually come first.

Still, it can be difficult to distinguish one condition from the other. If VCI is suspected, doctors often order an MRI scan of the brain to check for evidence of stroke or an MR or CT angiogram to look for narrowing in the arteries that lead to and serve the brain.

Treatment of VCI focuses on preventing further damage from occurring. Stroke prevention is achieved by managing risk factors — high blood pressure, cigarette smoking, high cholesterol, and diabetes. Medications such as aspirin are often used to help reduce the risk of future strokes.

Currently, there aren't any drugs approved by the Food and Drug Administration to treat VCI once it develops. However, medications designed to treat the symptoms of Alzheimer's disease may also help people with VCI by boosting certain chemicals in the brain and improving memory.

Although VCI is recognized as a less common cause of dementia than Alzheimer's disease, it has the distinction of being more preventable. That is why it is important to talk to your doctor about risk factors for stroke and how to best avoid or control them.

— J.D. Bartleson, M.D., Neurology, Mayo Clinic, Rochester, Minn.