For most people, a blood pressure reading of 140/90 mmHg or higher is a risk factor for stroke. However, for diabetics or patients with chronic kidney disorders, a blood pressure of 130/80 mmHg is considered high and a stroke risk factor, as noted by the National Heart, Lung and Blood Institute. When taking blood pressure reading the top number is the systolic pressure and the bottom number is the diastolic pressure, which are measured in millimeters of mercury.
Normal blood pressure is given as 120/80, notes WebMD. High blood pressure is a risk factor for stroke because it damages arteries, which can make them more susceptible to bursting or the development of plaque that causes arteries to become more narrow, as noted by the American Heart Association. An ischemic stroke occurs when there is a clot in a blood vessel that carries blood to the brain. A hemorrhagic stroke is when a blood vessel ruptures in the brain.