High blood pressure. The most important controllable risk factor for stroke (brain attack) is controlling high blood pressure (140/90 or higher). High blood pressure can damage blood vessels (called arteries) that supply blood to the brain. According to the Centers for Disease Control and Prevention, reducing the systolic (or top number) blood pressure by 12 to 13 points can decrease the risk for a stroke by 37 percent.

Heart disease. Heart disease is the second most important risk factor for stroke, and the major cause of death among survivors of stroke. Heart disease and stroke have many of the same risk factors.

Diabetes mellitus. Diabetes is controllable, but having it increases the risk for stroke. People with diabetes have two to four times the risk of having a stroke than someone without diabetes. Blood pressure for people with diabetes should be 130/80 or less to reduce the risk of stroke. Talk with your health care provider on specific ways to manage your overall health and diabetes care.

Cigarette smoking. Apart from other risk factors, smoking almost doubles the risk for ischemic stroke (blockage of a blood vessel supplying blood to the brain). The use of oral contraceptives, especially when combined with cigarette smoking, greatly increases stroke risk.

History of transient ischemic attacks (TIAs). A person who has had one (or more) TIA is almost 10 times more likely to have a stroke than someone of the same age and sex who has not had a TIA.

High red blood cell count. A significant increase in the number of red blood cells thickens the blood and makes clots more likely, thus increasing the risk for stroke.

High blood cholesterol and lipids. High blood cholesterol and lipids increase the risk for stroke. High cholesterol levels can contribute to atherosclerosis (thickening or hardening of the arteries) caused by a buildup of plaque (deposits of fatty substances, cholesterol, calcium). Plaque buildup on the inside of the walls of arteries can decrease the amount of blood flow to the brain. A stroke occurs if the blood supply is cut off to the brain. Atherosclerosis is a slow, progressive disease that may start as early as childhood.

Lack of exercise, physical inactivity. Lack of exercise and physical inactivity increases the risk for stroke.

Obesity. Excess weight increases the risk for stroke.

Excessive alcohol use. More than two drinks per day raises blood pressure, and binge drinking can lead to stroke.

Drug abuse (certain kinds). Intravenous drug abuse carries a high risk of stroke from cerebral embolisms (blood clots). Cocaine use has been closely related to strokes, heart attacks, and a variety of other cardiovascular complications. Some of them, even among first-time cocaine users, have been fatal.

Abnormal heart rhythm. Various heart diseases have been shown to increase the risk of stroke. Atrial fibrillation (an irregular heartbeat) is the most powerful and treatable heart risk factor of stroke. About 15 percent of strokes occur in people with atrial fibrillation.

Cardiac structural abnormalities. Damaged heart valves can cause chronic heart damage, which can ultimately increase the risk of developing stroke. This is known as valvular heart disease. New evidence shows that heart structure abnormalities including patent foramen ovale and atrial septal defect may possibly increase risk for embolic stroke.

Age. For each decade of life after age 55, the chance of having a stroke more than doubles.

Race. African-Americans have a much higher risk of death and disability from a stroke than Caucasians, in part because the African-American population has a greater incidence of high blood pressure.

Gender. Stroke occurs more frequently in men, but more women than men die from stroke.

History of prior stroke. The risk of stroke for someone who has already had one is many times that of a person who has not had a stroke.

Heredity/genetics. The chance of stroke is greater in people who have a family history of stroke.

Where a person lives. Strokes are more common among people living in the southeastern United States than in other areas. This may be due to regional differences in lifestyle, race, cigarette smoking, and diet.

Temperature, season, and climate. Stroke deaths occur more often during periods of extreme temperatures.

Socioeconomic factors. There is some evidence that strokes are more common among low-income people than among more affluent people.