09/28/2011 04:23 pm ET Updated Dec 06, 2017

Blood Pressure Just Slightly High? It Could Still Up Stroke Risk

Having blood pressure that is just slightly higher than normal could still spell trouble in terms of stroke risk, according to a comprehensive scientific review released Wednesday.

Much is known about the link between hypertension (a reading of 140/90 millimeters of mercury or above) and stroke, the third leading cause of death in the U.S. High blood pressure can damage arteries, causing them to burst or clog, which is why the American Heart Association calls it the top modifiable risk factor for stroke.

Less, however, is known about the potential long-term health impact of prehypertension, which is defined as systolic pressure of 120 to 139 mmHg, or diastolic pressure between 80 and 89 mmHg. The condition affects approximately a quarter of all American adults.

In recent years, some experts have recommended that slightly elevated blood pressure have its own separate clinical category, so doctors can identify those at risk for full-blown high blood pressure as well as problems like heart attack and stroke.

But according to Dr. Bruce Ovbiagele, one of the study's authors and a professor in the department of neurosciences at UC San Diego's School of Medicine, many are wary of the distinction.

"Right from the beginning, the introduction of prehypertension was met with a lot of skepticism," he wrote in an email to the HuffPost. "Critics and skeptics were concerned that prehypertension was simply being used to label otherwise healthy people with normal blood pressure as 'unhealthy,' without any compelling reason for doing so."

With this in mind, Ovbiagele and his colleagues combed through 12 major studies from around the globe to determine if people with slightly elevated blood pressure are indeed at higher risk of stroke and, if so, by how much.

Overall their results, published in the journal Neurology, suggest that people with prehypertension are at 55 percent higher risk of experiencing a stroke than those with normal blood pressure. And within that larger group, they found a range: People at the higher end of prehypertension (systolic of 130 to 139 mmHg or diastolic of 85 to 89) were at 79 percent increased risk of future stroke, while those at the lower end did not see much increased risk.

"Patients who fall in the higher range should strongly consider checking their blood pressure regularly and adopting beneficial lifestyle practices," Ovbiagele said, explaining that may mean measures like reducing salt intake to no more than two grams of sodium daily and maintaining a normal weight.

"Modifying one's lifestyle as noted is relatively harmless," he continued, "and could lower not just the risk of future strokes, but possibly other complications ... including heart attacks, heart failure and kidney disease."