Two-thirds had high blood pressure, defined as a top reading of 140 or more when the study began (it’s now 130 under new guidelines adopted last fall.) Their pressures were measured once a year during the study – a strength of this work over some previous research that just relied on people to say whether they had high pressure or not.
After each participant died, researchers examined their brains for areas of dead tissue caused by lack of blood supply. These blighted areas can be tiny and cause no symptoms, so they’re sometimes called evidence of “silent strokes.”
About half of the study participants had one or more of these, and the risk was greater for those with higher blood pressure. For example, people with an average top reading of 147 had a 46percent greater risk of having one or more of the bad spots than those with an average top reading of 134. People with higher bottom blood pressure readings also had a greater risk for this problem.