A stroke, sometimes called a brain attack, happens when blood flow to a part of your brain is cut off. Without the oxygen in blood, brain cells start dying within minutes. Two out of 3 people who survive a stroke have a disability, like paralysis or trouble talking.
Each year, some 800,000 people in the U.S. have a first or repeat stroke. Experts say we can prevent 80% of them.
A stroke can happen in two main ways: Something blocks the flow of blood, or something causes bleeding in the brain.
Ischemic stroke. In almost 9 out of 10 strokes, a blood vessel that takes blood to your brain gets plugged. It can happen 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. A “bleeding stroke” is less common but 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, or TIA. This "mini stroke" results from a temporary blockage. It doesn't cause permanent brain damage. But it raises your odds of having a stroke by many times.
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:
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 itself also 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.
Weight and exercise. If you're a man with a waist bigger than 40 inches or a woman with a belly size above 35 inches, your stroke risk may be especially high. You can lower your odds by working out every day. Take a brisk 30-minute walk, or do muscle-strengthening exercises like pushups and working with weights.
Medications. Blood thinners used to prevent blood clots can sometimes make a stroke more likely through bleeding. Studies have linked hormone therapy for menopause symptoms like hot flashes with a higher risk of strokes. Even low-dose estrogen in birth control pills may make your odds go up.
Age. Anyone could have a stroke, even babies in the womb. Generally, your chances go up as you get older. They double every decade after age 55.
Family. Strokes can run in families. You and your relatives may share a tendency to get high blood pressure or diabetes. Some strokes can result from a genetic disorder that blocks blood flow to the brain.
Gender. Women are slightly less likely to have a stroke than men of the same age. But women have strokes at a later age, which make them less likely to recover and more likely to die as a result.
Race. Strokes affect African-Americans and non-white Hispanic Americans much more often than any group in the U.S. Sickle cell disease, a genetic condition that can narrow arteries and interrupt blood flow, is also more common in these groups, and in people whose families came from the Mediterranean, the Middle East, or Asia.