Causes of Stroke

A stroke happens when blood flow to a part of your brain is cut off. Without the oxygen in blood, brain cells start dying within minutes. To help prevent a stroke, learn about the causes and the things that can raise your odds of getting one.

A stroke can happen in two main ways: Something blocks the flow of blood, or something causes bleeding in the brain.

Ischemic stroke. In 8 out of 10 strokes, a blood vessel that takes blood to your brain gets plugged. It happens when fatty deposits in arteries break off and travel to the brain or when poor blood flow from an irregular heartbeat forms a blood clot.

Hemorrhagic stroke. It’s less common than an ischemic stroke but can be more serious. A blood vessel in your brain balloons up and bursts, or a weakened one leaks. Uncontrolled high blood pressure and taking too much blood thinner medicine can lead to this kind of stroke.

Some people have what’s called a transient ischemic attack (TIA). This “mini stroke” is due to a temporary blockage. It doesn’t cause permanent brain damage, but it raises your odds of having a full-scale stroke.

You can treat some conditions that make you more likely to have a stroke. Other things that put you at risk can’t be changed:

  • High blood pressure. Your doctor may call it hypertension. It’s the biggest cause of strokes. If your blood pressure is typically 130/80 or higher, your doctor will discuss treatments with you.
  • Tobacco. Smoking or chewing it raises your odds of a stroke. Nicotine makes your blood pressure go up. Cigarette smoke causes a fatty buildup in your main neck artery. It also thickens your blood and makes it more likely to clot. Even secondhand smoke can affect you.
    Heart disease. This condition includes defective heart valves as well as atrial fibrillation, or irregular heartbeat, which causes a quarter of all strokes among the very elderly. You can also have clogged arteries from fatty deposits.
  • Diabetes. People who have it often have high blood pressure and are more likely to be overweight. Both raise the chance of a stroke. Diabetes damages your blood vessels, which makes a stroke more likely. If you have a stroke when your blood sugar levels are high, the injury to your brain is greater.

CDC: “Stroke.”
National Institute of Neurological Disorders and Stroke: “Brain Basics: Preventing Stroke.”
Cleveland Clinic: “Know Your Risk Factors for Stroke,” “Transient Ischemic Attack,” “Understanding Stroke,” “What is a Stroke?”
Merck Manuals Online: “Stroke: Introduction.”
National Stroke Association: “Am I at risk for a stroke?” “Hemorrhagic stroke,” “What Is Stroke?” “Stroke.”
American Heart Association: “Stroke Risk Factors.”
American Stroke Association: “Let’s Talk About Risk Factors for Stroke,” “Stroke Risks.”
American College of Cardiology: “Understanding Risks of Stroke and Blood Thinners.”
American Society of Hematology: “Sickle Cell Anemia.”

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