Scientists have linked prehypertension - or slightly raised blood pressure - with an increased risk of stroke.
The results of 12 different studies looking at blood pressure and stroke risk were combined so that the results of 518,520 adults were analysed.
The researchers found that people with blood pressure slightly above the normal level had a 50% higher chance of suffering a stroke than those with normal blood pressure levels.
The risk was greater for people with prehypertension who were under the age of 65. The risk of this group having a stroke compared with people with normal blood pressure was 80% higher.
Study leader Dr Bruce Ovbiagele, from the University of California at San Diego, said: “These people may immediately benefit from blood pressure-lowering methods, such as reducing their salt intake and weight, to help reduce their risk of stroke.”
Risk factors such as age, gender, diabetes, obesity, cholesterol and smoking were all taken into consideration for the research, which was published online in the journal neurology.