(Xinhua)
Updated: 2007-11-29 21:06

Alzheimer's patients with high blood pressure, which reduces blood flow to the brain, are more vulnerable to the effects of the disease, researchers reported Wednesday.

Researchers using a magnetic resonance imaging technique to measure blood flow in the brains of 68 older adults found cerebral blood flow was substantially decreased in all patients with high blood pressure and was the lowest in Alzheimer's patients with high blood pressure.

"What we think may be happening is hypertension reflects an extra hit to the brain," said Cyrus Raji of the University of Pittsburgh, who led the study.

The study compared Alzheimer patients to adults with normal cognitive function and a group with mild cognitive impairment, defined as a transitional stage between dementia and normal, age-related deficits in language, attention and reasoning.

Half of the patients in each of the three groups had high blood pressure and half did not.

The researchers used an imaging program called arterial spin-labeled MRI, which calculates blood flow per minute in a section of brain tissue and does not require use of a contrast agent. Contrast agents are compounds the patient receives either orally or intravenously to make the MRI scan easier to see.

About 50 million Americans have hypertension, in which the blood circulates through the arteries with too much force, according to the National Heart, Lung and Blood Institute. The condition increases the risk for heart attack, stroke and aneurysm.