Researchers in the Netherlands have learned less blood flow to the brain may lead to dementia.

Dementia is a loss of cognitive functions, such as thinking, remembering and reasoning. Although many conditions can produce these symptoms, Alzheimer's disease is the most common cause of dementia. Some patients with Parkinson's disease also develop dementia.

In the Dutch study, researchers examined 17 patients with late-onset dementia (dementia occurring after age 75), another 16 seniors of the same age with optimal cognitive function, and 15 healthy younger individuals. Researchers used magnetic resonance imaging (MRI) scans to measure blood flow to the brain and brain damage in each person.

Average total blood flow to the brain was 742 milliliters per minute in the healthy group. Blood flow in the two elderly groups averaged 496 milliliters per minute, or 246 milliliters per minute lower than the younger group. In patients with dementia, average blood flow to the brain was 443 milliliters per minute, or 108 milliliters per minute lower than seniors of the same age with optimal cognitive function.

Although patients with dementia have been shown to require less blood flow as the brain becomes less active, the new evidence shows decreased blood flow may lead to some types of dementia.

"The findings emphasize the importance of monitoring both high and low blood pressure in older adults," says Aart Split, M.D., lead study author. "Possible causes of low cerebral blood flow include heart failure and a narrowing of cerebral or cervical arteries."

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