Most Americans dread having a stroke far more than a heart attack, research suggests, and with good reason. While improved treatment and rehabilitation now offer more hope for stroke victims, up to half still experience substantial and permanent mental or physical disabilities, and only 10 percent recover completely. In contrast, 90 percent of heart-attack survivors return to work and resume normal lives. And while heart attacks are more common, strokes are more deadly. As a result, the numbers who die during or soon after those events are similar.

Yet most people focus far more on preventing heart attacks than strokes. "Many people assume that if they're taking steps to protect their heart they're also doing all that they can to protect their brain," says Larry B. Goldstein, M.D., the main author of the American Stroke Association's 2006 guidelines on preventing a first stroke. While many heart-attack and stroke risk factors do overlap, there are many important differences.

Two of the most ominous factors--clogged neck arteries and an abnormal heart rhythm called atrial fibrillation--threaten only the brain. Both of those factors can easily be overlooked by doctors and patients alike. When they are detected, they're often mistreated, in part because the therapies are complex and controversial.

Several other less-familiar or less-established risk factors also apply only or mainly to stroke, including oral contraceptive use, migraines, and sickle-cell disease. And some clearly shared risk factors--such as high blood pressure and cholesterol levels--can affect stroke and heart-attack risk in different ways.

Knowing those differences can help you lower your risk not only of overt strokes but probably also of insidious "silent" ones. Recent studies suggest that those small, unnoticed strokes are extremely common, and can gradually impair mental and physical performance as early as middle age.

While most people think of stroke as an obviously catastrophic event, brain scans have shown that some 10 percent of Americans in their 50s and 40 percent of those in their 80s have had a silent stroke that causes no immediate symptoms. In contrast, just 2 percent of those in their 50s and 15 percent of those in their 80s have had an overt, symptomatic stroke.

Silent strokes slowly damage the brain in subtle ways, detectable on a magnetic resonance imaging (MRI) test, that can eventually impair physical and mental performance. In one 2005 study, researchers found that even people in their 40s and 50s who had such strokes performed worse on a variety of cognitive tests than those without that history.

Focusing on stroke prevention can be especially important for people at high stroke risk, including African-Americans and people with a strong family history of such attacks. (To determine your stroke risk, take the online test provided by the National Heart Lung and Blood Institute.)

Stopping smoking is one crucial step in reducing your risk of stroke. Here are a dozen other steps that can help ward off both overt and silent strokes.

Hypertension triggers up to 40 percent of all strokes, depending on age, and it threatens the brain even more than the heart. That's partly because high blood pressure raises the risk of both types of overt stroke: ischemic, caused by blood-vessel blockages, and hemorrhagic, the less common but deadlier kind, caused by a ruptured blood vessel. But only about 60 percent of Americans with hypertension are treated, and only about half of those get it under control. And stroke risk increases even at high-normal pressure.

If your systolic pressure (the upper number) is more than 120 mm Hg or your diastolic (lower) number exceeds 80 mm Hg, try to lower the pressure by exercising, losing excess weight, cutting back on salt, and eating lots of produce, whole grains, and low-fat dairy products. If your blood pressure is higher than 140/90 mm Hg, talk with your doctor about possibly adding antihypertensive medication.

Atrial fibrillation, an abnormal heartbeat, threatens the brain far more than the heart by encouraging the formation of blood clots that can travel from the heart and plug arteries in the brain. So your doctor should check for abnormal rhythms by listening to your heart through a stethoscope while feeling the pulse in your wrist, and following up if necessary with an electrocardiogram.

Even more worrisome, many people diagnosed with atrial fibrillation do not receive adequate treatment, in part because the therapy is frequently complicated and controversial. But recent guidelines, described in "Treating atrial fibrillation" (see below) have helped to clarify those options.

About 5 percent of ischemic strokes stem from clogging of one or both carotid arteries, the large neck vessels that feed the brain. Your doctor should listen with a stethoscope to the blood flow through those arteries and order an ultrasound if a noise, or bruit, is heard. People at very high risk, such as those with a history of stroke or transient ischemic attack (TIA)--a strokelike episode that resolves itself within 24 hours and causes no permanent damage--should talk with their physician about undergoing the test even if there's no bruit.

A surgical procedure called carotid endarterectomy to scrape out the artery blockage can prevent stroke in people who have either severe clogging or moderate blockage plus a history of stroke or TIA. But in recent years some physicians have turned to carotid angioplasty plus stenting rather than carotid endarterectomy.

Experts had hoped that the procedure--the insertion of a miniature balloon to crush the blockage and a tiny tube to prop the artery open--would prove safer and at least as effective as endarterectomy. But studies have now dashed that hope. Our medical consultants say that the balloon plus stent should be reserved for individuals who cannot undergo endarterectomy because of high surgical risk.


Elevated levels of the "bad" LDL cholesterol, a strong predictor of heart disease in both sexes, do not appear to raise stroke risk in men. But a February 2007 Harvard study of some 30,000 women found that those with the highest LDL levels had a greater risk of stroke than those with the lowest. Effective LDL-reducing steps include losing excess weight, cutting back on saturated and trans fat, and consuming plenty of fiber, soy protein, and plant stanols and sterols, which are abundant in nuts and added to certain margarines and other foods.


The Harvard women's study found no evidence that women with high levels of the "good" HDL cholesterol were less likely to have a stroke. But previous studies have linked low HDL with increased risk of stroke in men (and of heart attack in both sexes). Lifestyle steps that can boost HDL include doing aerobic exercise, losing weight, stopping smoking, eating lots of whole grains and produce, and limiting the intake of refined grains and trans fats.


LDL-reducing statin drugs such as lovastatin and simvastatin cut stroke risk by about 20 percent, not only in women but also in men. One possible reason: Statins reduce arterial inflammation, which appears to increase the risk of both stroke and heart attack, and they may slightly boost HDL levels, recent research indicates.

Preventing diabetes--by eating properly, exercising regularly, and controlling your weight--almost surely protects the brain as much as the heart. Moreover, aggressively treating elevated blood pressure and high cholesterol levels reduces the risk of stroke in individuals who already have diabetes.

Low-dose aspirin therapy helps prevent heart attack in men over age 40 and women over 65. It also reduces the risk of stroke in anyone who's already suffered one or had a TIA. But aspirin's ability to prevent a stroke when there's no such history appears limited to women. The treatment can make sense for women at high risk of stroke or heart disease and normal or low risk of gastrointestinal bleeding. The decision on aspirin for men depends mainly on their heart risk.

Those vitamins, notably folic acid, B6, and B12, can lower blood levels of homocysteine, which may contribute to clogged arteries and blood clots. No studies have yet shown that taking B vitamins lowers stroke risk. But a 2006 analysis found that stroke death rates have slightly declined since manufacturers began adding folic acid to grains in the U.S. about a decade ago.

Grains and beans also contain lots of vitamin B6. However, people over age 50 often have trouble absorbing vitamin B12 from food, so they should consider taking a modest daily B12 supplement or regularly eating B12-fortified foods.

That can indicate sleep apnea, in which the throat temporarily and repeatedly closes at night, depriving the brain of oxygen. Sleep apnea multiplies stroke risk, perhaps by causing drug-resistant hypertension and worsening atrial fibrillation. Losing weight and sleeping on your side may help. Or see a sleep specialist, who may recommend using a special airway opener at night or even undergoing throat surgery.

Women who are older than age 35, smoke cigarettes, or have high blood pressure should avoid birth-control products containing estrogen, which can slightly increase stroke risk. Good alternatives include progestin-only pills or intrauterine devices (IUDs).

Premenopausal women with migraines appear to have a slightly elevated stroke risk, though there's no evidence that controlling the headaches reduces the risk. Still, people with migraines should be especially vigilant about taking steps to help ward off a stroke.