Blood Flow to Brain Linked to Dementia

The amount of blood flowing into the brain may be closely linked to the development of dementia caused by conditions such as Alzheimer's disease.

A new study showed that older adults with dementia had significantly reduced blood flow into the brain compared with older adults with normal brain function or young adults.

Dementia is a condition that causes a loss of brain function -- such as thinking, remembering, and reasoning -- that interferes with daily activities. Alzheimer's disease is the most common cause, but other causes of dementia also exist, such as Parkinson's disease.

Researchers say the findings suggest that decreased blood flow to the brain may contribute to the brain damage associated with dementia.

"This gives us a clue to the genesis of dementia," says researcher Aart Spilt, MD, of Leiden University Medical Center in the Netherlands, in a news release. "The findings emphasize the importance of monitoring both high and low blood pressure in older adults."

Possible causes of low blood flow to the brain include heart failure and a narrowing of the arteries leading to the brain caused by heart disease.

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Blood Flow Linked to Brain Damage

In the study, researchers used brain imaging to measure blood flow into the brain as well as brain damage in three groups: 17 older adults with dementia; 16 older adults with normal brain function; and 15 young, healthy adults.

The results, published in the September issue of Radiology, showed that the older adults with dementia not only had more extensive brain damage than the other two groups, as expected, but they also had a significantly lower rate of blood flow into the brain.

The average blood flow into the brain among the dementia group was 443 milliliters per minute, which was 108 milliliters per minute lower than older adults of the same age with good brain function. In comparison, average blood flow in the brain was 742 milliliters per minute among the healthy, young adults.

Researchers say previous studies have shown that older people with dementia may require less blood flow as the brain becomes less active. But Spilt says this study provides evidence that decreased blood flow may also lead to some types of dementia.

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By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCES: Spilt, A. Radiology, September 2005; vol 236: pp 990-995. News release, Radiological Society of North America.