MONDAY, Dec. 19 (HealthDay News) -- Blood pressure changes in middle age can affect your lifetime risk for heart disease and stroke, a new study suggests.

U.S. researchers analyzed data from almost 62,000 people whose blood pressure readings were tracked for an average of 14 years.

People who kept or lowered their blood pressure to normal levels by age 55 had the lowest lifetime risk (22 percent to 41 percent) for heart disease. The risk for people who had high blood pressure at age 55, however, was 42 percent to 69 percent.

When all blood pressure levels were factored in, the overall lifetime heart disease risk for people over the age of 55 was about 53 percent for men and about 40 percent for women.

"This study adds to our existing knowledge that hypertension is the most important modifiable risk factor for cardiovascular disease, including coronary heart disease and stroke," said expert Dr. Robert Graham, an internist at Lenox Hill Hospital in New York City. "Unfortunately, many patients do not take this 'silent disease' seriously because they usually don't see or feel the effects of their hypertension until some catastrophic outcome has occurred," he added.

Among the other findings:

• Women generally had higher increases in middle age than men, and women who have high blood pressure by early middle age (average age 41) have a higher lifetime risk for heart disease (49 percent) than those who have maintained normal blood pressure up to age 55.
• At an average age of 55, 26 percent of men had normal blood pressure, as did 41 percent of women, while about 49 percent of men and 48 percent of women had prehypertension.
• Nearly 70 percent of men who develop high blood pressure in middle age will experience a cardiovascular event such as a stroke or heart attack by age 85, the team found.

The study appears Dec. 19 in the journal Circulation.

"Taking blood pressure changes into account can provide more accurate estimates for lifetime risk of cardiovascular disease, and it can help us predict individualized risk, and thus, individualized prevention strategies," study author Norrina Allen, an assistant professor in the department of preventive medicine at the Northwestern University Feinberg School of Medicine, in Chicago, explained in a journal news release.

"Both avoiding hypertension during middle age or delaying the onset of the development of hypertension appear to have a significant impact on an individual's remaining lifetime risk for CVD," Allen noted.

Graham agreed. He said that hypertension in middle age "can affect one's lifetime risk for heart disease and stroke. Fortunately, with medications and lifestyle changes, patients who control their blood pressure during middle age had the lowest lifetime risk of cardiovascular disease, while those with an increase in blood pressure had the highest risk."

More information

The U.S. National Heart, Lung, and Blood Institute offers a guide to lowering high blood pressure.