WEDNESDAY, Sept. 28 (HealthDay News) -- Having blood pressure
readings that are just slightly above normal -- a condition known
as prehypertension -- appears to raise the risk of stroke, new
Normal blood pressure is a systolic blood pressure (top number)
below 120 mmHg and a diastolic blood pressure (bottom number) below
Prehypertension is slightly above that -- systolic blood
pressure between 120 and 139 mmHg or diastolic blood pressure
between 80 and 89 mmHg.
For this study, researchers reviewed 12 previous studies about
blood pressure and stroke involving more than half a million adults
from the United States, Japan, China and India.
The investigators found that people with prehypertension and no
prior history of cardiovascular disease were 55 percent more likely
to have a stroke than people with normal blood pressure, even after
taking into account factors such as age, gender, diabetes, obesity,
cholesterol and smoking.
When the researchers split the people with prehypertension into
two groups -- those at the lower end of the prehypertensive range
and those at the upper end -- they found those in the upper range
(130 to 139 mmHg systolic and 85 to 89 mmHg diastolic) had a 79
percent increased risk of stroke.
The risk of stroke was not shown to be significantly increased
in the lower end of the prehypertensive group.
"The message for patients is that stroke is the fourth leading cause of death and a leading cause of disability in the United States, and if you do fall into [the prehypertensive] category you should take it very seriously and strongly consider a change in lifestyle to try and reduce your risk of stroke," said senior study author Dr. Bruce Ovbiagele, a professor of neurosciences at University of California, San Diego.
Ovbiagele and his colleagues also found that the impact of
higher than normal blood pressure on stroke was the most pronounced
among those under age 65. Their risk of stroke was nearly 80
percent higher than people in that age bracket with normal blood
In people older than 65, researchers believe other factors
obscure the impact of prehypertension. "Age is such a powerful
factor putting people at risk of stroke that we think it overwhelms
any added contribution from the slightly higher blood pressure,"
The study is published in the Sept. 28 online edition and the
Oct. 4 print issue of the journal
Between 25 percent and 46 percent of the study participants were
prehypertensive. Prior research has found that about 25 percent of
U.S. adults have prehypertension, according to background
information in an accompanying editorial.
Experts said it was premature to suggest that everyone with
slightly elevated blood pressure be put on medications.
Instead, current recommendations call for people with
prehypertension to make changes such as quitting smoking,
exercising at least 30 minutes daily, limiting alcohol, reducing
salt intake, and maintaining a normal body mass index.
Medications are recommended when lifestyle changes fail to bring
down blood pressure, and in people with diabetes or kidney disease,
said Dr. Amytis Towfighi, an assistant professor of neurology at
University of Southern California's Keck School of Medicine, who
co-wrote the accompanying editorial.
"Lifestyle changes have been shown to lower blood pressure in individuals with prehypertension," Towfighi said.
American Academy of Family Physicians has tips on
lowering high blood pressure.