Lower Blood Pressure Reduces Brain Damage After Stroke

French study finds less loss of nerve cells, preserving mental function

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By Ed Edelson
HealthDay Reporter

WEDNESDAY, Sept. 7, 2005 (HealthDay News) -- Lowering blood pressure in the years after a stroke reduces the death of brain cells that can cause loss of mental function, a new study finds.

Using MRI to get detailed pictures of the brain, French researchers report that people who got a drug to lower pressure after a stroke or a mini-stroke had significantly fewer "white matter hyperintensities" -- abnormalities that indicate tissue damage.

It's a small study that needs verification in larger trials, said Dr. Christophe Tzourio, lead author of the report and director of the neuroepidemiology unit at INSERM, the French counterpart to the U.S. National Institutes of Health.

"But we were surprised and quite pleased with the effect," he said.

The findings appear in the Sept. 7 issue of the journal Circulation.

The trial included 192 people with an average age of 60 who had had a stroke or mini-stroke in the previous five years. Roughly half were given perindopril, an ACE-inhibitor drug to lower blood pressure, while the other half received a placebo, an inactive substance.

Each participant underwent an MRI brain scan at the start of the study, and another one 36 months later.

The researchers report that the volume of new white matter spots in the brains of people who got the drug was just one-fifth that of people who got the placebo -- 0.4 cubic millimeters versus 2 cubic millimeters.

But the study's potential power to influence medical practice may be limited because of the small number of participants, Tzourio said. "We want to have a large trial," he said. "We probably need to have several hundred or several thousands of participants. In terms of cost, that would be very, very expensive."

The basic principle -- that lowering high blood pressure is beneficial -- still applies, he said, especially for people who have mini-strokes, formally called transient ischemic attacks (TIA).

"If you have a TIA, you obviously need your blood pressure lowered, more than if you have not had a TIA," Tzourio said.

Daniel Lackland, a professor of epidemiology at the Medical University of South Carolina and a spokesman for the American Stroke Association, agreed heartily.

"This finding is consistent with everything else we know," Lackland said. "We've known for some time that lowering blood pressure successfully reduces the risk of dementia. This paper suggests that the loss of white matter is the link between high blood pressure and dementia."

The study also opens up a new area of research, he said, such as studies to determine whether lowering blood pressure can reduce the incidence of Alzheimer's disease and other forms of dementia.

But the other advantages of keeping blood pressure under control -- notably a reduction in heart disease and stroke -- show that "you should get your blood pressure as low as possible," Lackland said.

But there's a bit of controversy about lowering blood pressure for all people in the first hours after a stroke, added Dr. Argye B. Hillis, a neurologist at Johns Hopkins Hospital in Baltimore. A subset of patients -- those whose stroke is caused by blockage of a major brain blood vessel -- might suffer more damage if the blood pressure is reduced in the acute stage of the stroke, she said.

But over the longer run -- the months and the years after a stroke -- the evidence supports lowering blood pressure, she said.

More information

The American Heart Association has more on high blood pressure.

SOURCES: Christope Tzourio, M.D., Ph.D., director, neurepidemiology unit, INSERM, Paris, France; Daniel Lackland, Ph.D, professor of epidemiology, Medical University of South Carolina, Charleston; Argye B. Hillis, M.D., neurologist, Johns Hopkins Hospital, Baltimore; Sept. 7, 2005, Circulation

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