The study, directed by Dr. Seamus P. Whelton, cardiologist and epidemiologist at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease in Baltimore, followed a cohort of 1,457 middle-aged men and women initially free of atherosclerotic vascular disease and known risk factors for 14.5 years. As the participants aged, their risk factors for heart disease increased, along with calcium deposits in their coronary arteries and cardiovascular events like heart attacks and strokes.
The research team focused on increases in systolic blood pressure with age, adjusting the data for changes in other heart risks. They found that for every 10 mm increase in systolic blood pressure, the risk of calcium deposits and cardiovascular events rose accordingly. Compared with people with systolic pressures of 90 to 99 mm, those with pressures of 120 to 129 mm were 4.58 times more likely to have experienced a cardiovascular event.
Still, Dr. Whelton said in an interview that it would be wrong to focus preventive strategies on blood pressure alone. People with high blood pressure, he said, “are also more likely to have higher cholesterol and blood glucose levels. The ideal strategy would focus on all risk factors — blood cholesterol, blood sugar and blood pressure. Maintaining a healthful diet, exercising, not smoking and consuming alcohol only in moderation would improve all the risk factors for cardiovascular disease.”
Levels of what doctors consider a healthy systolic blood pressure have been falling for about half a century. In August 1950, a report in JAMA suggested that labeling systolic blood pressures of 140, 150 or 160 mm as abnormally high is “arbitrary, particularly when age is concerned.” The authors suggested that raising acceptable blood pressure levels for people over 40 “would result in a decrease in the reported incidence of hypertension and thus allay some of the widespread and unnecessary fear regarding high blood pressure.”
The latest blood pressure advisory, issued in 2017 by the American Heart Association and American College of Cardiology, considers a systolic blood pressure of 120 mm the upper limit of normal, and defines 130 mm and above as high blood pressure that warrants treatment with lifestyle measures or medication.
In an editorial accompanying the new study, Dr. Daniel W. Jones, hypertension specialist at the University of Mississippi Medical Center who helped formulate the current blood pressure guidelines, wrote, “the risk imposed by a blood pressure level below the currently defined hypertensive level is continuous beginning with a systolic blood pressure as low as 90 mm mercury.”
Dr. Jones said in an interview, “Normal blood pressure can be in the 90s, which is what it is in young healthy women, before the vascular system is damaged by elevated blood pressure over the years. Prevention should start with children, with a healthy diet low in salt and regular exercise, and adults should avoid gaining weight with age, which I realize is very difficult to do in our toxic food society.”