Slightly high BP raises chances of stroke

Even if your blood pressure (BP) is slightly elevated, you may be prone to a stroke, new research says.

Prehypertension is a clinical category to describe patients whose BP is elevated but still considered within normal range.

People with prehypertension have a 55 percent higher chance of experiencing a stroke than people without it, University of California School of Medicine noted.

That hypertension or abnormally high BP is a major risk for cardiovascular diseases and strokes is well-known, but much less is known about the dangers of prehypertension, the journal Neurology reports.

A stroke is a condition where a blood clot or ruptured artery or blood vessel interrupts blood flow to the brain. A lack of oxygen and glucose (sugar) flowing to the brain leads to brain damage, causing impairment in speech, movement and memory.

"Generally speaking, the higher the blood pressure, the greater the risk of death and disease, possibly starting from within the normal blood range," said Bruce Ovbiagele, professor of neurosciences.

Researchers identified 12 relevant prospective cohort studies of prehypertension, derived from the general population. Four were from the US, five from Japan, two from China and one from India, according to a California statement.
The combined studies involved more than 518,000 participants and covered periods ranging from 2.7 years to 32 years, with stroke occurrences documented.

The prevalence of prehypertension in the studies ranged from 25 to 46 percent.

"Overall, people who had prehypertension (in the studies) were at a 55 percent higher risk of experiencing a future stroke than people without prehypertension," said Ovbiagele. "This result was held regardless of sex, race, ethnicity, blood pressure type or the type of stroke."

The health risk was measurably greater for those whose blood pressure levels were at the high end of the "normal" spectrum.