A stroke, sometimes called a “brain attack,” happens when an artery to the brain becomes blocked or ruptures. As a result, blood flow is cut off to a part of the brain, depriving cells of oxygen and glucose from the blood supply. If the cut-off is brief, brain cells may be stressed but able to recover. But if cells are deprived for more than 3 or 4 minutes, they may die, resulting in permanent damage to the brain. In some cases of stroke, certain functions are lost, but other areas of the brain can learn to do the tasks previously handled by the damaged area.
Two types of stroke exist:
Ischemic stroke: About 80% of strokes are ischemic strokes. This type happens when a blood vessel in the brain develops a clot that cuts off blood flow to cells.
Hemorrhagic stroke: The remaining 20% are hemorrhagic strokes, which happen when a weakened blood vessel in the brain bursts. When the vessel bleeds or hemorrhages suddenly, surrounding brain tissue can become damaged. Hemorrhagic stroke is the most serious type of stroke.
How do you know if you are at risk for having a stroke? There are two types of risk factors: controllable and uncontrollable. Some stroke risk factors, such as high blood pressure and smoking, can be controlled by medication or lifestyle changes. Other risk factors, such as age and race, cannot be changed.
Controllable risk factors:
- High blood pressure (hypertension): High blood pressure, defined as a reading of 140/90 or greater, is the leading risk factor for stroke. When blood pushes too forcefully against the walls of the arteries, it can weaken them and eventually lead to stroke. Adults should strive to keep their blood pressure below 140/90, or 130/80 or below if they’re at higher risk for stroke. An ideal reading is 120/80 or lower.
- Atherosclerosis: With this major risk factor for stroke, fatty plaques that build up inside the artery walls will block or narrow the vessels, which can lead to stroke.
- Heart disease: Coronary heart disease, heart failure, dilated cardiomyopathy (an enlarged heart), and other heart diseases place people at higher stroke risk, compared to those with normal hearts.
- High cholesterol: Excess cholesterol raises one’s chances of heart disease and atherosclerosis. High cholesterol contributes to plaque buildup in arteries, which can block blood flow to the brain and cause stroke.
- Smoking or tobacco use:Smoking lowers oxygen levels in the blood, forcing the heart to work harder and enabling blood clots to form more readily. Cigarette smoke can also worsen atherosclerosis. According to the National Stroke Association, smokers have twice the risk of stroke as nonsmokers.
- Atrial fibrillation (AFib): This disorder, marked by an irregular heartbeat, makes a person five times more likely to have a stroke, according to the National Stroke Association.With AFib, the heart’s two upper chambers beat rapidly and unpredictably, which allows blood to pool in the heart. The pooled blood can form clots that travel to the brain and cause a stroke.
- Diabetes: People with diabetes face higher risk of stroke because they often have other health problems and stroke risk factors, including high blood pressure, high cholesterol, and heart disease.
- Overweight or obesity: Extra weight, along with being sedentary, raises the chances of high blood pressure or diabetes.
- Blood disorders: Blood disorders, such as sickle cell disease or severe anemia, can cause stroke, if left untreated.
- Excessive alcohol: Some research has linked too much alcohol to increased stroke risk. Women should limit themselves to one alcoholic drink per day; men, two per day.
- Drugs: Certain medications, such as anticoagulants, can raise stroke risk. Birth control pills and patches place some women at greater risk for stroke, especially if they’re over age 35 or have high blood pressure, diabetes, or high cholesterol, or if they smoke. Illicit drugs, such as cocaine, heroin, or amphetamines, are risk factors, too.Uncontrollable risk factors:
- Age: A stroke can happen at any age, even in children, but it becomes more common as people get older. For each decade after age 55, the chance of stroke roughly doubles.
- Gender: Strokes are more common in men, but women make up more than half of all stroke deaths.
- Race:African-Americans are much more likely to die from strokes than whites, partly because African-Americans have a higher risk of hypertension, diabetes, and obesity.
- Family history: Stroke risk rises if a person’s parent, grandparent, or sibling has had a stroke or if a family member had a heart attack at an early age.
- Previous stroke or heart attack: The risk of a second stroke is much higher if a person has already had a past stroke or heart attack.
- Transient ischemic attack (TIA): TIA, which is sometimes called a “mini-stroke,” may be a precursor to an ischemic stroke. TIA stems from a temporary blockage of the brain’s blood supply. Symptoms are similar to those of an actual stroke, but usually last only a few minutes or hours, with no lasting effects. But it’s a serious warning sign. Up to 33% of people with “mini-strokes” will go on to have a more severe stroke, according to the National Institutes of Health.
- Artery abnormalities: The chance of a hemorrhagic stroke goes up if a person has an aneurysm (a bulge in a weakened area of an artery’s walls) within the skull. Arteriovenous malformation (an abnormal connection between arteries and veins) is another risk factor for hemorrhagic stroke.
- Fibromuscular dysplasia:With this medical disorder, some arteries develop improperly. Fibrous tissue grows in artery walls, making them narrower. As a result, blood flow through the arteries is reduced, which can lead to stroke.
- Patent foramen ovale (hole in the heart): Typically, this condition has no symptoms, and impacts about 15% to 20% of all people. But a person with a hole, or flap-like opening between the two upper chambers of the heart, faces increased risk of stroke or TIA. A blood clot can pass through this opening, travel to the brain, and cause a stroke. Those with patent foramen ovale might have a stroke without any obvious risk factors.
If you suspect you’re at risk for stroke, or if you have a family history of stroke, talk to your doctor about your medical history and specific concerns. Your doctor can help you manage your risk factors and develop a treatment plan if necessary.
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