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Risk Factors
Some conditions as well as some lifestyle factors can put people at a
higher risk for stroke. The most important risk factors for stroke are high
blood pressure, heart disease, diabetes, and cigarette smoking. Persons who
have already had a stroke need to control the risk factors in order to lower
their risk of having another stroke. All persons can take steps to lower
their risk for stroke. High Blood Pressure
High blood pressure, or hypertension, is a major risk factor for stroke. It
is a condition where the pressure of the blood in the arteries is too high.
There are often no symptoms to signal high blood pressure. About 60 million
people in the United States have high blood pressure. Lowering blood pressure can
lower the risk of stroke. Medicines to lower blood pressure can decrease the risk of
stroke among those with high blood pressure. See our
high blood pressure fact
sheet.
Heart Disease
Common heart disorders such as coronary artery disease can also increase a
person's risk for stroke. Coronary artery disease (CAD) occurs when the
arteries that supply blood to the heart muscle become hardened and narrowed
due to the buildup of plaque. Plaque (a mixture of fatty substances,
including cholesterol and other lipids) and blood clots can build up inside
the artery walls, causing thickening, hardening, and loss of elasticity.
They can result in decreased or blocked blood flow and lead to a heart
attack. Also, heart problems such as valve defects, irregular heart beat,
and enlargement of one of the heart's chambers can result in blood clots
that may break loose and cause a stroke. Persons with heart disease may be
given medicines such as aspirin to help prevent clots from forming.
See our heart disease fact
sheet. Atrial Fibrillation
A heart condition known as atrial fibrillation is a major concern. Atrial
fibrillation is irregular beating of the upper chambers, or atria, of the heart.
When the atria quivers instead of beating in a regular pattern, blood is not fully
pumped out of them and may pool and clot. The clots can then leave the heart
and travel to the brain, causing a stroke. Atrial fibrillation affects as
many as 2.2 million Americans. About 15 percent of stroke patients have
had atrial fibrillation before they experience a stroke.
See our
fact sheet on this condition. Diabetes
Diabetes is another disease that increases a person's risk for stroke. With
diabetes, the body does not make enough insulin, cannot use its own
insulin as well as it should, or both. This causes sugars to be unavailable
to the body tissues and to build up in the blood. People with diabetes have 2 to 4 times the risk of stroke
compared to people without diabetes. Further, having diabetes can worsen the
outcome of stroke. For more information about diabetes, see
CDC’s diabetes program Web site. Tobacco Use
Smoking almost doubles a person's risk for ischemic stroke, independently
of other risk factors.
Cigarette smoking increases the risk of stroke by promoting
atherosclerosis and increasing the levels of blood clotting factors, such
as fibrinogen. Also, nicotine raises blood pressure, and carbon monoxide
reduces the amount of oxygen that blood can carry to the brain. For more
information about tobacco use and quitting, see
CDC’s tobacco intervention and
prevention source Web site. Other Factors
Blood Cholesterol Levels
Some strokes can be caused by a narrowing of the arteries through the
buildup of plaque, a mixture of fatty substances, including cholesterol and
other lipids. This is called atherosclerosis. Plaque and blood clots build
up inside the artery walls, causing thickening, hardening, and loss of
elasticity. These can lead to decreased blood flow and to stroke if they
occur in the arteries to the brain. Cholesterol is a waxy substance
produced by the liver. It is needed by the body, and the liver makes
enough cholesterol for the body's needs. Excess cholesterol—usually from
eating foods that contain high levels of cholesterol and saturated fats—contributes to
atherosclerosis. There are two major kinds of cholesterol, one that is good,
and one that is bad when there is too much of it. A higher level of
high–density lipoprotein cholesterol, or HDL, is considered good. However,
higher levels of low–density lipoprotein, or LDL, can lead to
atherosclerosis and stroke. A lipoprotein profile can be done to
measure several different kinds of cholesterol as well as triglycerides
(another kind of fat found in the blood).
See our cholesterol fact sheet.
Alcohol
Generally, excessive alcohol use can lead to an increase in blood
pressure, which increases the risk for stroke. More information on alcohol
can be found at
CDC’s alcohol and public health Web site. Genetic Risk Factors
Stroke can run in families. Genes play a role in stroke risk factors such
as high blood pressure, heart disease, diabetes, and vascular conditions.
It is also possible that an increased risk for stroke within a family is
due to factors such as a common sedentary lifestyle or poor eating habits,
rather than hereditary factors. Find out more about genetics and diseases
on CDC's genomics and disease
prevention Web site.
Page last reviewed: October 10, 2007
Page last modified: February 9, 2007
Content source: Division for Heart Disease and Stroke Prevention,
National Center for Chronic Disease Prevention and
Health Promotion
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