A stroke is the interruption of the flow of blood to any part of the brain, which causes damage to brain tissue.  Today, some call a stroke a "brain attack" to illustrate its seriousness and its relationship to heart attack (the interruption of blood flow to the heart).  Stroke causes one out every fifteen deaths in the U.S., is the third leading cause of death in most developed countries, and the leading cause of disability in adults. The damage to brain tissue can lead to various problems, such as impaired speech and mobility, changes in vision, reflexes, and eye movements, decreased sensation, and weakness or even paralysis in one side of the body.

In most cases, the blood flow is interrupted by a blood clot blocking an artery in the brain or leading to the brain.  There are four main arteries leading to the brain: two carotid arteries in the front of the neck and two vertebral arteries in the back of the neck.  Blockage in these arteries, especially in the carotid arteries, is often caused by atherosclerosis, an accumulation of "plaque" (deposits of fat) on the inside wall of the arteries; this is the same condition that can lead to heart attack.  The type of stroke caused by blockage in an artery is called an ischemic stroke. There is a second, less common type, called a hemorrhagic stroke, in which the blood flow is interrupted by bleeding in the brain, caused by a ruptured blood vessel.

The risk factors (things that increase your chance of getting a disease) for stroke include:

• High blood pressure: This is the leading modifiable risk factor for stroke.
• Age: The chance of having a stroke goes up with age and doubles for every decade after 55.
• Family history: The chance of having a stroke goes up (is higher than average) if your family members had one.
• High cholesterol: This can cause fat to build up in the arteries, leading to blockage and stroke (as well as heart attack).
• Diabetes:  This disease can cause high blood pressure, blocked arteries (atherosclerosis), and inability to break down blood clots.
• Heart disease:  This disease can result from atherosclerosis and doubles your risk of stroke.
• Smoking: Cigarette smoke damages the cardiovascular system, which can lead to heart disease and stroke.
• Previous stroke:  Having a stroke places you at higher risk of having another one, compared to people who have not had a stroke.
• Race: The chance of getting the disease is higher for African-Americans because they have a higher rate of diabetes and high blood pressure.
• Certain medications: Among the drugs that promote clot formation are birth control pills, especially if you're over 35 and a smoker.  But newer, low dose pills create a much lower risk.
• Gender: Generally, men are more likely to have a stroke, women are more likely to die of one, and women have a higher than normal risk during pregnancy and the weeks immediately after it.
• Life style:  Among life style risk factors are smoking, alcohol abuse, illicit drugs such as cocaine, and uncontrolled stress.

There are preventative measures (things that decrease your risk of getting a disease) you can take against stroke.  For information about them, go to Key Point 3.