A stroke occurs when blood flow to the brain is disrupted, depriving brain cells of oxygen. There are two main types of stroke - one caused by a blockage cutting off blood flow, and one caused by bleeding in the brain. Symptoms depend on the affected brain region and may include weakness, vision issues, speech problems or headaches. Risk factors include age, sex, race, diabetes, prior stroke, high blood pressure, heart conditions, smoking and obesity. Controlling risk factors through lifestyle changes such as diet, exercise, not smoking and managing medical conditions can help prevent stroke.