BRAIN BASICS

If you’re like most Americans, you plan your future. When you 

take a job, you examine its benefit plan. When you buy a home, you 

consider its location and condition so that your investment is safe. 

Today, more and more Americans are protecting their most important 

asset—their brain. Are you? 

Stroke ranks as the fourth leading killer in the United States. 

A stroke can be devastating to individuals and their families, robbing 

them of their independence. It is the most common cause of adult 

disability. Each year more than 700,000 Americans have a stroke, 

with about 160,000 dying from stroke-related causes. Officials at the 

National Institute of Neurological Disorders and Stroke (NINDS) 

are committed to reducing that burden through biomedical research. 

What is a Stroke?

A stroke, or “brain attack,” occurs when blood circulation to 

the brain fails. Brain cells can die from decreased blood flow and 

the resulting lack of oxygen. There are two broad categories of 

stroke: those caused by a blockage of blood flow and those caused 

by bleeding into the brain. A blockage of a blood vessel in the brain 

or neck, called an ischemic stroke, is the most frequent cause of stroke 

and is responsible for about 80 percent of strokes. These blockages 

stem from three conditions: the formation of a clot within a blood 

vessel of the brain or neck, called thrombosis; the movement of a clot 

from another part of the body such as the heart to the brain, called 

embolism; or a severe narrowing of an artery in or leading to the brain, 

called stenosis. Bleeding into the brain or the spaces surrounding the 

brain causes the second type of stroke, called hemorrhagic stroke. 

Two key steps you can take will lower your risk of death or 

disability from stroke: control stroke’s risk factors and know stroke’s 

warning signs. Scientific research conducted by the NINDS has 

identified warning signs and a large number of risk factors. 

National Institute of Neurological Disorders and Stroke • National Institutes of Health

Preventing Stroke

A stroke, or

“brain attack,”

occurs when

blood circulation to the

brain fails.
BRAIN BASICS

What are Warning Signs of a Stroke? 

Warning signs are clues your body sends that your brain is not 

receiving enough oxygen. If you observe one or more of these signs of 

a stroke or “brain attack,” don’t wait, call a doctor or 911 right away! 

• Sudden numbness or weakness of face, arm, or leg, 

especially on one side of the body

• Sudden confusion, or trouble talking or understanding speech

• Sudden trouble seeing in one or both eyes

• Sudden trouble walking, dizziness, or loss of balance 

or coordination 

• Sudden severe headache with no known cause

Other danger signs that may occur include double vision, drowsiness, 

and nausea or vomiting. Sometimes the warning signs may last only a 

few moments and then disappear. These brief episodes, known as transient 

ischemic attacks or TIAs, are sometimes called “mini-strokes.” Although 

brief, they identify an underlying serious condition that isn’t going away 

without medical help. Unfortunately, since they clear up, many people 

ignore them. Don’t. Paying attention to them can save your life. 

What are Risk Factors for a Stroke? 

A risk factor is a condition or behavior that occurs more frequently 

in those who have, or are at greater risk of getting, a disease than in 

those who don’t. Having a risk factor for stroke doesn’t mean you’ll 

have a stroke. On the other hand, not having a risk factor doesn’t mean 

you’ll avoid a stroke. But your risk of stroke grows as the number and 

severity of risk factors increases. 

Some factors for stroke can’t be modified by medical treatment or 

lifestyle changes.

• Age. Stroke occurs in all age groups. Studies show the risk of 

stroke doubles for each decade between the ages of 55 and 

85. But strokes also can occur in childhood or adolescence. 

Although stroke is often considered a disease of aging, the 

risk of stroke in childhood is actually highest during the 

perinatal period, which encompasses the last few months 

of fetal life and the first few weeks after birth.

• Gender. Men have a higher risk for stroke, but more women 

die from stroke. Men generally do not live as long as women, 

so men are usually younger when they have their strokes and 

therefore have a higher rate of survival.

Sometimes the 

warning signs 

[of a stroke] may 

last only a few 

moments and 

then disappear.
BRAIN BASICS

• Race. People from certain ethnic groups have a higher risk of 

stroke. For African Americans, stroke is more common and 

more deadly—even in young and middle-aged adults—than 

for any ethnic or other racial group in the United States. Studies 

show that the age-adjusted incidence of stroke is about twice 

as high in African Americans and Hispanic Americans as in 

Caucasians. An important risk factor for African-Americans 

is sickle cell disease, which can cause a narrowing of arteries 

and disrupt blood flow. The incidence of the various stroke 

subtypes also varies considerably in different ethnic groups.

• Family history of stroke. Stroke seems to run in some families. 

Several factors may contribute to familial stroke. Members of 

a family might have a genetic tendency for stroke risk factors, 

such as an inherited predisposition for high blood pressure 

(hypertension) or diabetes. The influence of a common lifestyle 

among family members also could contribute to familial stroke.

Some of the most important treatable risk factors for stroke are: 

• High blood pressure, or hypertension. Hypertension is by far 

the most potent risk factor for stroke. Hypertension causes a 

two-to four-fold increase in the risk of stroke before age 80. 

If your blood pressure is high, you and your doctor need to 

work out an individual strategy to bring it down to the normal 

range. Some ways that work: Maintain proper weight. Avoid 

drugs known to raise blood pressure. Eat right: cut down on 

salt and eat fruits and vegetables to increase potassium in your 

diet. Exercise more. Your doctor may prescribe medicines that 

help lower blood pressure. Controlling blood pressure will 

also help you avoid heart disease, diabetes, and kidney failure.

• Cigarette smoking. Cigarette smoking causes about a two-fold 

increase in the risk of ischemic stroke and up to a four-fold 

increase in the risk of hemorrhagic stroke. It has been linked 

to the buildup of fatty substances (atherosclerosis) in the 

carotid artery, the main neck artery supplying blood to the 

brain. Blockage of this artery is the leading cause of stroke 

in Americans. Also, nicotine raises blood pressure; carbon 

monoxide from smoking reduces the amount of oxygen your 

blood can carry to the brain; and cigarette smoke makes your 

blood thicker and more likely to clot. Smoking also promotes 

High blood 

pressure is 

by far the 

most potent 

risk factor 

for stroke.
BRAIN BASICS

aneurysm formation. Your doctor can recommend programs 

and medications that may help you quit smoking. By quitting, 

at any age, you also reduce your risk of lung disease, heart 

disease, and a number of cancers including lung cancer. 

• Heart disease. Common heart disorders such as coronary 

artery disease, valve defects, irregular heart beat (atrial 

fibrillation), and enlargement of one of the heart’s chambers 

can result in blood clots that may break loose and block 

vessels in or leading to the brain. Atrial fibrillation—which is 

more prevalent in older people—is responsible for one in four 

strokes after age 80, and is associated with higher mortality 

and disability. The most common blood vessel disease is 

atherosclerosis. Hypertension promotes atherosclerosis and 

causes mechanical damage to the walls of blood vessels. Your 

doctor will treat your heart disease and may also prescribe 

medication, such as aspirin, to help prevent the formation 

of clots. Your doctor may recommend surgery to clean out 

a clogged neck artery if you match a particular risk profile. 

If you are over 50, NINDS scientists believe you and your 

doctor should make a decision about aspirin therapy. A doctor 

can evaluate your risk factors and help you decide if you 

will benefit from aspirin or other blood-thinning therapy. 

• Warning signs or history of TIA or stroke. If you experience 

a TIA, get help at once. If you’ve previously had a TIA or 

stroke, your risk of having a stroke is many times greater 

than someone who has never had one. Many communities 

encourage those with stroke’s warning signs to dial 911 for 

emergency medical assistance. If you have had a stroke in 

the past, it’s important to reduce your risk of a second stroke. 

Your brain helps you recover from a stroke by asking the 

unaffected brain regions to do double duty. That means a 

second stroke can be twice as bad. 

• Diabetes. In terms of stroke and cardiovascular disease, having 

diabetes is the equivalent of aging 15 years. You may think this 

disorder affects only the body’s ability to use sugar, or glucose. 

But it also causes destructive changes in the blood vessels 

throughout the body, including the brain. Also, if blood glucose 

levels are high at the time of a stroke, then brain damage is 

Stroke strikes fast.

You should, too.

Call 911.
BRAIN BASICS

usually more severe and extensive than when blood glucose is 

well-controlled. Hypertension is common among diabetics and 

accounts for much of their increased stroke risk. Treating diabetes 

can delay the onset of complications that increase the risk of stroke. 

• Cholesterol imbalance. Low-density lipoprotein cholesterol 

(LDL) carries cholesterol (a fatty substance) through the 

blood and delivers it to cells. Excess LDL can cause cholesterol 

to build up in blood vessels, leading to atherosclerosis. 

Atherosclerosis is the major cause of blood vessel narrowing, 

leading to both heart attack and stroke.

• Physical inactivity and obesity. Obesity and inactivity are 

associated with hypertension, diabetes, and heart disease. 

Waist circumference to hip circumference ratio equal to or 

above the mid-value for the population increases the risk 

of ischemic stroke three-fold.

Do You Know Your Stroke Risk?

Some of the most important risk factors for stroke can be 

determined during a physical exam at your doctor’s office. If you 

are over 55 years old, the worksheet in this pamphlet can help you 

estimate your risk of stroke and show the benefit of risk factor control. 

The worksheet was developed from NINDS-supported work in 

the well-known Framingham Study. Working with your doctor, you 

can develop a strategy to lower your risk to average or even below 

average for your age. 

Many risk factors for stroke can be managed, some very 

successfully. Although risk is never zero at any age, by starting early 

and controlling your risk factors you can lower your risk of death or 

disability from stroke. With good control, the risk of stroke in most 

age groups can be kept below that for accidental injury or death. 

Americans have shown that stroke is preventable and treatable. 

In recent years, a better understanding of the causes of stroke has 

helped Americans make lifestyle changes that have cut the stroke 

death rate nearly in half. 

Scientists at the NINDS predict that, with continued attention to 

reducing the risks of stroke and by using currently available therapies 

and developing new ones, Americans should be able to prevent 

80 percent of all strokes. 

Americans 

should be 

able to 

prevent 

80 percent 

of all strokes.
BRAIN BASICS

Score your stroke risk for the next 10 years–MEN

Key: SBP = systolic blood pressure (score one line only, untreated or treated); Diabetes = history of diabetes; 

Cigarettes = smokes cigarettes; CVD (cardiovascular disease) = history of heart disease; AF = history of atrial fibrillation; 

LVH = diagnosis of left ventricular hypertrophy; untrd = untreated; trtd = treated with medication

Points 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

Age 54-56 57-59 60-62 63-65 66-68 69-72 73-75 76-78 79-81 82-84 85

SBP-untrd 97-105 106-115 116-125 126-135 136-145 146-155 156-165 166-175 176-185 186-195 196-205

or SBP-trtd 97-105 106-115 113-117 118-123 124-129 130-135 136-142 143-150 151-161 162-176 177-205

Diabetes No Yes

Cigarettes No Yes

CVD No Yes

AF No Yes

LVH No Yes

Your

Points

10-Year

Probability

Your

Points

10-Year 

Probability

Your

Points

10-Year

Probability

1 3% 11 11% 21 42%

2 3% 12 13% 22 47%

3 4% 13 15% 23 52%

4 4% 14 17% 24 57%

5 5% 15 20% 25 63%

6 5% 16 22% 26 68%

7 6% 17 26% 27 74%

8 7% 18 29% 28 79%

9 8% 19 33% 29 84%

10 10% 20 37% 30 88%

Compare

with Your

Age

Group

Average

10-Year

Probability

of Stroke

55-59 5.9%

60-64 7.8%

65-69 11.0%

70-74 13.7%

75-79 18.0%

80-84 22.3%

Source: D’Agostino, R.B.; Wolf, P.A.; Belanger, A.J.; & Kannel, W.B. “Stroke Risk Profile: The Framingham Study.” Stroke,

Vol. 25, No. 1, pp. 40-43, January 1994.
BRAIN BASICS

Score your stroke risk for the next 10 years-WOMEN

Key: SBP = systolic blood pressure (score one line only, untreated or treated); Diabetes = history of diabetes; 

Cigarettes = smokes cigarettes; CVD (cardiovascular disease) = history of heart disease; AF = history of atrial fibrillation; 

LVH = diagnosis of left ventricular hypertrophy; untrd = untreated; trtd = treated with medication

Points 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

Age 54-56 57-59 60-62 63-64 65-67 68-70 71-73 74-76 77-78 79-81 82-84

SBP-untrd 95-106 107-118 119-130 131-143 144-155 156-167 168-180 181-192 193-204 205-216

or SBP-trtd 95-106 107-113 114-119 120-125 126-131 132-139 140-148 149-160 161-204 205-216

Diabetes No Yes

Cigarettes No Yes

CVD No Yes

AF No Yes

LVH No Yes

Your

Points

10-Year

Probability

Your

Points

10-Year 

Probability

Your

Points

10-Year

Probability

1 1% 11 8% 21 43%

2 1% 12 9% 22 50%

3 2% 13 11% 23 57%

4 2% 14 13% 24 64%

5 2% 15 16% 25 71%

6 3% 16 19% 26 78%

7 4% 17 23% 27 84%

8 4% 18 27%

9 5% 19 32%

10 6% 20 37%

Compare

with Your

Age

Group

Average

10-Year

Probability

of Stroke

55-59 3.0%

60-64 4.7%

65-69 7.2%

70-74 10.9%

75-79 15.5%

80-84 23.9%

This example helps you assess your risk of stroke. Tally your points to score your 

stroke risk over the next 10 years. 

Martha, age 65, wanted to determine her risk for having a stroke, so she took 

this stroke risk profile. This is how she arrived at her 10-year probability risk for 

having a stroke: 

Age 65 4 points

SBP – treated, 107-113 2 points

Diabetes - No 0 points

Cigarettes - Yes 3 points

CVD -No 0 points

AF - Yes 6 points

LVH -No 0 points

TOTAL 15 points

Interpretation: 15 points carries a 16 percent, 10-year probability of having a stroke.

If Martha quits smoking she can reduce her points to 12, which carries a 9 percent, 

10-year probability of having a stroke.

Her current point total does not mean Martha will have a stroke, but serves as a 

wake-up call to ways she can lower her risk or even prevent a stroke. A lower percent 

score doesn’t mean that Martha won’t have a stroke, only that she is at a lower risk of 

having one. 

No matter what your score is, it is important to work on reducing your risk factors 

as Martha did in this example by quitting smoking.
BRAIN BASICS

The National Institute of Neurological 

Disorders and Stroke (NINDS)

Since its creation by Congress in 1950, the NINDS—a component 

of the National Institutes of Health—has grown to become the leading 

supporter of neurological research in the United States. Most research 

funded by the NINDS is conducted by scientists in public and private 

institutions such as universities, medical schools, and hospitals. 

Government scientists also conduct a wide variety of neurological 

research in the laboratories and branches of the NINDS itself. This 

research ranges from studies on the structure and function of single 

brain cells to tests of new diagnostic tools and treatments for those 

with neurological disorders. For more information, write or call the 

Institute’s Brain Resources and Information Network (BRAIN):

BRAIN

P.O. Box 5801

Bethesda, MD 20824

 800-352-9424

www.ninds.nih.gov

U.S. Department of Health and Human Services • Public Health Service

NIH Publication No. 11-3440b