Preventing Stroke
You can do it — if you know your risks and take steps to reduce them.
Stroke is the sudden interruption of oxygen to part of the brain — whether caused by the blockage of an artery supplying the brain (ischemic stroke) or bleeding in the brain from a ruptured blood vessel (hemorrhagic stroke). More than three million American women have had a stroke. It's the third most common cause of death in the United States, claiming the lives of nearly 100,000 women per year. It's also the nation's leading cause of long-term disability, robbing many survivors of their independence and causing dementia in up to 25% of them.
Like most other chronic conditions, stroke is caused by a combination of factors. Some are beyond our control. For example, stroke risk increases with age and is higher among African Americans. Blood vessel malformations and weaknesses, clotting disorders, and migraine headaches also increase the risk. So do a family history of stroke, a prior stroke, transient ischemic attack (TIA), and a heart attack or other heart condition (such as atrial fibrillation). But some of the most important risk factors — high blood pressure, high cholesterol, obesity, diabetes, smoking, and lack of exercise — are things we can do something about.
If you've had a stroke, you can cut your odds of having another by taking necessary medication as well as by changing your diet and other health habits. If you've never had a stroke, you can greatly reduce your risk of ever having one by leading a healthy lifestyle and having regular checkups to detect conditions that could lead to stroke, and then taking steps to control those conditions.
"Risk factors really matter, and many of the strongest ones can be modified. There's a lot you can do to help prevent stroke," says Dr. Tobias Kurth, assistant professor of medicine at Brigham and Women's Hospital and Harvard Medical School. In 2006, Dr. Kurth co-authored a study of lifestyle and stroke risk in women published in the Archives of Internal Medicine (July 10, 2006). Monitoring nearly 38,000 participants in the Women's Health Study for 10 years, he and his colleagues found that women with the greatest number of healthy habits were 71% less likely to have an ischemic stroke — the most common type — than those with the fewest. The women least likely to suffer a stroke were those who had a body mass index (BMI) of less than 22, had never smoked, exercised four or more times per week, had four to 10 alcoholic drinks per week, and ate a diet high in fiber, folic acid, and omega-3 fatty acids but low in saturated fat, trans fat, and refined carbohydrates.
The established causes don't account for all strokes. Clinicians suspect there are additional risk factors that haven't been identified. But there are many steps you can take to protect yourself based on the known risk factors.
Control Your Blood Pressure
High blood pressure damages the inner walls of blood vessels, setting in motion a cascade of problems (scarring, plaque buildup, and blood-vessel narrowing) that can culminate in stroke. Simply keeping your blood pressure under control reduces your stroke risk by 30% to 40%. Normal blood pressure is less than 120/80 millimeters of mercury (mm Hg). High blood pressure is 140/90 mm Hg or higher (130/80 or higher in people who have diabetes).
What to do. Have your blood pressure checked every two years if it's normal and at least yearly if it's elevated. Reduce your blood pressure through lifestyle changes (including regular exercise, reduced salt intake, and a healthy diet) and, if necessary, through medication — diuretics, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-receptor blockers, beta blockers, or alpha blockers. Losing weight — even a few pounds — also helps bring down blood pressure.
Lower Your Cholesterol
In 2007, researchers using data from the Women's Health Study reported that abnormal blood lipids as much as doubled the risk of ischemic stroke in apparently healthy women (Neurology, Feb. 20, 2007). This study is one of the first to show a clear link between cholesterol levels and stroke in women with no other cardiovascular conditions. The study also provides support for findings from clinical trials showing that cholesterol-lowering statins reduce the risk of stroke. The American Heart Association recommends that healthy women keep total cholesterol below 200 milligrams per deciliter (mg/dL); HDL cholesterol above 50 mg/dL; LDL cholesterol below 100 mg/dL; and triglycerides below 150 mg/dL.
What to do. Have your cholesterol levels checked every five years using a fasting lipoprotein profile. Healthy eating (see "What's in a healthy diet?") is important, and so is regular exercise, which helps control your weight — another risk factor for stroke.
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What's in a healthy diet?
The emphasis these days is on establishing a healthy eating pattern over time, rather than simply counting calories or demonizing particular foods. A diet with cardiovascular benefits is low in saturated fat, avoids trans fat, and includes the following:
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Three to six servings per day of grains, at least half of them whole grains (for example, brown rice, bulgur, 100% whole-wheat bread, and whole-grain cereal) rather than refined grains such as white bread, white rice, and pasta made with refined flour.
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Five servings or more per day of fruits and vegetables. Whole fruits (as opposed to juice) and dark green and orange vegetables tend to be high in fiber, nutrients, and antioxidants.
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Four servings per week of nuts, seeds, and legumes (dried beans and peas). You may also use these foods as a substitute for meats and poultry.
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At least two servings per week of fish, especially those rich in omega-3 fatty acids, such as salmon and mackerel. If you don't like fish, try plant-based sources of omega-3 fats, such as soybeans, tofu, walnuts, and ground flaxseeds.
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Small amounts of healthy fats, such as those found in olive and canola oils (monounsaturated fat) and corn, sunflower, and other vegetable oils (polyunsaturated fat).
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Medications are an option if (a) you haven't reached your target cholesterol and triglyceride levels after three months of lifestyle change; or (b) your LDL cholesterol is 190 mg/dL or higher; or (c) you have one or more of the following risk factors: heart disease, prior stroke, diabetes, high triglycerides, or low HDL cholesterol. Several medications, including statins, niacin, and fibrates, can reduce LDL and triglyceride levels and raise HDL.
In people who've had an ischemic stroke or TIA, statins have been shown to reduce the risk of stroke even beyond their cholesterol-lowering effect, so stroke patients often leave the hospital with a prescription for a statin. According to a study published in the journal Stroke (online, Aug. 30, 2007), patients who stopped taking statins within the first month or two after discharge increased their risk of dying in the first year after a stroke.
For guidelines on treating unfavorable cholesterol levels, visit www.nhlbi.nih.gov/guidelines/cholesterol.
Avoid Tobacco Smoke
Smoking can more than double your chances of having a stroke. It also boosts blood pressure, lowers beneficial HDL cholesterol, damages the protective lining of the blood vessels, and makes blood more prone to clotting — all risk factors for stroke. Even if you don't smoke yourself, exposure to other people's tobacco smoke can increase your risk.
What to do. Stop smoking, and don't inhale others' smoke. In the Nurses' Health Study, women who stopped smoking lowered their risk of stroke by 25% within one to two years; after five or more years, their risk was about the same as someone who had never smoked. Experts recommend a three-pronged approach to quitting: Wear a nicotine patch or chew nicotine gum to help suppress the urge to smoke; join a support group or seek counseling; and learn techniques that can steer you away from thoughts of smoking or the activities that trigger it. (For a free online smoking cessation program that encompasses these recommendations, visit www.ffsonline.org.)
Exercise
Even modest amounts of exercise can help protect against stroke. In the Nurses' Health Study, women who walked briskly at least one hour per week were less likely to have a stroke than women who didn't exercise at all; the faster the pace, the lower the risk. Physical activity helps control weight, makes blood less likely to clot, lowers blood pressure, and increases HDL levels.
What to do. Get at least 30 minutes of moderate-intensity physical activity on most days. If you exercise longer or more vigorously, you'll get even greater health benefits. Examples of moderate-intensity exercise are brisk walking (three to four miles per hour), bicycling at five to nine miles per hour, and swimming. If you've had a stroke, exercise can help you recover as well as reduce your risk for another cardiovascular event. Aim for 20 to 60 minutes of continuous or accumulated exercise three to seven days a week. If you have a stroke-related disability, work with a physical therapist to design a program tailored to your situation.
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Should you take aspirin to prevent stroke?
If you've had an ischemic stroke or heart attack, a daily low-dose aspirin can lower your risk of a second one. But the evidence for aspirin use in healthy women is mixed. In 2005, the Women's Health Study tested a low dose of aspirin taken every other day in healthy women ages 45 and older. Overall, women taking aspirin reduced their risk for ischemic stroke (the most common type) by 24% and their risk for a TIA by 22%; on the other hand, hemorrhagic stroke risk rose by 24%. For women ages 65 and over, the cardiovascular benefits of aspirin were considerably higher: 34% fewer heart attacks and 30% fewer ischemic strokes.
In healthy women under age 65, the risks of regular aspirin use (bruising, gastrointestinal bleeding, and increased chance of hemorrhagic stroke) may outweigh its modest benefits. But healthy women ages 65 or over and younger women with a strong family history of cardiovascular disease should discuss aspirin therapy (an 81-mg baby aspirin daily) with their clinician.
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Maintain a Healthy Weight
According to findings from the Women's Health Study, obese women — those with a BMI of 30 or higher — are 50% more likely to have a stroke than those with a body weight in the healthy range (a BMI under 25). But current weight isn't the only concern: Gaining weight also matters. In the Nurses' Health Study, women who added 22 to 24 pounds as adults were 70% more likely to have an ischemic stroke, compared with women whose weight remained stable.
What to do. Be physically active, and eat a healthy diet with no more calories than you expend. To get an idea of the number of calories needed to maintain your present weight, multiply your weight in pounds by 15. For example, a moderately active 130-pound woman requires 1,950 calories (130 × 15 = 1,950). If you want to lose weight, cut your intake by 500 calories per day. If you don't want to go that far, try eating 250 fewer calories per day and getting an additional 30 minutes of moderate-intensity exercise on most days. Don't allow your total intake to fall below 1,200 calories a day unless you're under the supervision of a clinician.
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Should a narrowed carotid artery be treated?
The carotid arteries on either side of the neck channel blood to the brain. A stroke can occur when one of them is blocked, so surgery to remove an obstruction that narrows the artery reduces the risk of a recurrence. The procedure is called carotid endarterectomy. It may also be performed when ultrasound imaging indicates severe narrowing of a carotid artery and reduced blood flow to the brain, even in a person who has not had a stroke or TIA. This surgery carries serious risks, including the possibility of triggering a heart attack or stroke, so if you're advised to undergo the procedure, it's important to get a second opinion.
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Control Other Risk Factors
The impact of other risk factors may depend on your lifestyle and medical history.
Limit alcohol. Moderate alcohol consumption (no more than one drink per day for women) will probably lower your risk for ischemic stroke, but the same amount will increase your risk for hemorrhagic stroke (the less common but often more devastating type). Having more than two drinks a day increases the risk of both types.
Weigh the risks of hormone therapy. The Women's Health Initiative trial of estrogen-plus-progestin was halted in 2002 because of cardiovascular problems among women taking the hormone combination. Hormone therapy is now recommended only for short-term symptom relief and at the lowest effective dose. But we don't know yet whether lower doses are any safer. If you're considering hormone therapy to control hot flashes or other menopausal symptoms, discuss the risks and benefits with your clinician.
Treat atrial fibrillation. Atrial fibrillation is an abnormal heart rhythm that can result in the formation of clots in the upper chambers (atria) of the heart. If a clot breaks free and lodges in an artery to the brain, it can cause an ischemic stroke. If you have atrial fibrillation, your clinician will probably prescribe either warfarin (Coumadin), an anticoagulant, or aspirin, which makes blood platelets less likely to form clots. Medications that prevent blood clotting can reduce the risk of ischemic stroke by 68% in people with this condition.