A rise in blood pressure during middle age significantly raises the risk of having a heart attack or a stroke during a person’s lifetime, report Northwestern University School of Medicine (Illinois, USA) researchers. Previous estimates of a person's risk of cardiovascular disease were based on a single blood pressure measurement.: the higher the blood pressure reading, the greater the risk. Norrina Allen and colleagues analyzed data from 61,585 participants in the Cardiovascular Lifetime Risk Pooling Project. Starting with baseline blood pressure readings at age 41, researchers measured blood pressure again at age 55, then followed the patients until the occurrence of a first heart attack or stroke, death or age 95. Men who developed high blood pressure in middle age or who started out with high blood pressure had a 70% risk of having a heart attack or stroke, compared to a 41% risk for men who maintained low blood pressure or whose blood pressure decreased during the time period. Women who developed high blood pressure had almost a 50% risk of a heart attack or stroke, compared to a 22% risk for those who kept their blood pressure low or saw a decrease. People that maintain or reduce their blood pressure to normal levels by age 55 have the lowest lifetime risk for a heart attack or a stroke.  The study offers a new understanding on the importance of maintaining low blood pressure early in middle age to prevent heart disease later in life. Writing that: “Individuals who experience increases or decreases in [blood pressure] in middle age have associated higher and lower remaining [lifetime risk] for [cardiovascular disease],” the study authors urge that: “Prevention efforts should continue to emphasize the importance of lowering [blood pressure] and avoiding or delaying the incidence of hypertension in order to reduce the [lifetime risk] for [cardiovascular disease].”