High blood pressure may contribute to memory loss and other declines in brain function in people 45 and older, according to a study. The higher the reading, the more likely the individuals were to show impairment.
With each 10-point increase in diastolic blood pressure, the odds of cognitive difficulties grew by 7 percent, according to the report published today in the journal Neurology. This measurement is the force exerted on arteries when the heart is at rest.
The study builds on previous research probing the connection between blood pressure and brain function. The research thus far has yielded conflicting results, said Georgios Tsivgoulis, an assistant professor of neurology at the University of Alabama in Birmingham, and a lead study author, in an e-mail today. The study is noteworthy because it analyzed more than 19,000 participants, Maria C. Carrillo, senior director of medical and scientific relations for the Alzheimer's Association in Chicago, said today in a telephone interview.
“It lends further support to what we had already really thought was the case,” said Carrillo. “That is that high blood pressure, and certainly cerebrovascular diseases, do contribute to increased risk of Alzheimer's disease.”
When diastolic blood pressure rises, it can cause arterial walls in the brain to thicken faster than they do naturally with age, which may lead to reduced blood flow and tissue death, according to the report. Systolic blood pressure, the force on arteries when the heart beats, didn't show a connection to brain function.
The research, funded by the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health, included 19,836 participants ages 45 and older. It used data from a national evaluation of stroke risk, called Reasons for Geographic and Racial Differences in Stroke, which tested participants' blood pressure and assessed their brain function.
More research is needed on risk factors of declining brain function and Alzheimer's disease, Carrillo said. More than 5.3 million people in the U.S. have Alzheimer's, with one person developing the disease every 70 seconds, the Alzheimer's Association says on its Web site. It was the sixth-leading cause of deaths in 2007, overtaking diabetes.
High blood pressure is defined as more than 90 millimeters of mercury (mm Hg) diastolic pressure or more than 140 mm Hg systolic pressure, according to the American Heart Association.
“It's never too late to change your lifestyle habits, and it's never too late to change the trajectory of cognitive decline,” Carrillo said. “Research has shown us that even late in life -- exercise, eat healthy -- you can actually give yourself years of health.”
While the cause of high blood pressure is unknown in more than 90 percent of cases, doctors recommend it may be controlled by reducing fat and salt intake and not smoking, the association says on its Web site.
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