Risk Factors:

New or recurrent strokes affect about 780,000 Americans every year. On average, someone in the United States has a stroke every 40 seconds. While age is the major risk factor, people who have a stroke are likely to have more than one risk factor.

Age

People most at risk for stroke are older adults, particularly those with high blood pressure, who are sedentary, overweight, smoke, or have diabetes. Older age is also linked with higher rates of post-stroke dementia. Younger people are not immune, however. About 28% of stroke victims are under age 65.

Gender

In most age groups except older adults, stroke is more common in men than in women. However, it kills more women than men, regardless of ethnic groups. This may be partly due to the fact that women tend to live longer than men, and stroke is more common among older adults. Women account for about 6 in 10 stroke deaths. For younger women, birth control pills and pregnancy can increase the risk of stroke.

Race and Ethnicity

All minority groups, including Native Americans, Hispanics, and African-Americans, face a significantly higher risk for stroke and death from stroke than Caucasians. African-Americans have twice the risk for first-time stroke as Caucasians. The differences in risk among all groups diminish as people age.

The greatest disparity in risk occurs in young adults. Younger African-Americans are two to three times more likely to experience a stroke than their Caucasian peers and four times more likely to die from one. They also face a higher risk for death from heart disease. African-Americans have a higher prevalence of obesity, diabetes, and hypertension than other groups. However, studies suggest that socioeconomic factors also affect these differences.

Family History

A family history of stroke or TIA is a strong risk factor for stroke.

Lifestyle Factors

Smoking. People who smoke a pack a day have almost two and a half times the risk for stroke as nonsmokers. Smoking increases both hemorrhagic and ischemic stroke risk. The risk for stroke may remain elevated for as long as 14 years after quitting, so the earlier one quits the better.

Diet. Unhealthy diet (saturated fat, high sodium) can contribute to heart disease, high blood pressure, and obesity, which are all risk factors for stroke.

Physical Inactivity. Lack of regular exercise can increase the risk of obesity, diabetes, and poor circulation, which increase the risk of stroke.

Alcohol and Drug Abuse. Alcohol abuse, including binge drinking, increases the risk of stroke. Drug abuse, particularly with cocaine or methamphetamine, is a major factor of stroke in young adults. Anabolic steroids, used for body-building and sports enhancement, also increase stroke risk.

Heart and Vascular Diseases

Heart disease and stroke are closely tied for many reasons. People who have one heart or vascular condition (high blood pressure, high cholesterol, heart disease, diabetes, peripheral artery disease) are at increased risk for developing other related conditions. Heart and vascular diseases that increase stroke risk include:

Prior Stroke. A history of a prior stroke or TIA significantly increases the risk for a subsequent stroke. People who have had at least one TIA are 10 times more likely to have a stroke than those who have not had a TIA.

Prior Heart Attack. People who have had a heart attack are at increased risk of stroke.

High Blood Pressure. High blood pressure (hypertension) of contributes to about 70% of all strokes. Hypertensive people have up to 10 times the normal risk of stroke, depending on the severity of the blood pressure in the presence of other risk factors. Hypertension is also an important cause of so-called silent cerebral infarcts, or blockages, in the blood vessels in the brain (mini-strokes) that may predict major stroke. Controlling blood pressure is extremely important for stroke prevention.

Unhealthy Cholesterol Levels. A high total cholesterol level increases the risk of developing atherosclerosis (“hardening of the arteries”) and heart disease. In atherosclerosis, fatty deposits (plaques) of cholesterol build up in the arteries of the heart.

Heart Disease. Coronary artery disease (heart disease), which is the end result of atherosclerosis increases stroke risk. Anti-clotting medications, which are used in heart disease treatment to break up blood clots, can increase the risk of hemorrhagic stroke.

Atrial Fibrillation. Atrial fibrillation, a major risk factor for stroke, is a heart rhythm disorder in which the atria (the upper chambers in the heart) beat very quickly and nonrhythmically. The blood pools instead of being pumped out, increasing the risk for formation of blood clots that break loose and travel toward the brain. Between 2 - 4% of patients with atrial fibrillation without any history of TIA or stroke will have an ischemic stroke over the course of a year. Of those with atrial fibrillation, the risk generally is highest in those older than age 75, with heart failure or enlarged heart, coronary artery disease, history of clots, diabetes, or heart valve abnormalities.

Structural Heart Problems. Dilated cardiomyopathy (enlarged heart), heart valve disorders, and congenital heart defects such as patent foramen ovalae (opening in chambers of heart) and atrial septal aneurysm (bulging of heart chamber) are risk factors for stroke.

Carotid Artery Disease and Peripheral Artery Disease. Carotid artery disease is a serious risk factor for stroke. Atherosclerosis can cause fatty build-up in the carotid arteries of the neck, which can lead to blood clots that block blood flow and oxygen to the brain. People with peripheral artery disease, which occurs when atherosclerosis narrows blood vessels in the legs and arms, are at increased risk of carotid artery disease and subsequently stroke.

Diabetes

Heart disease and stroke are the leading causes of death in people with diabetes.. Diabetes is second only to high blood pressure as the main risk factor for stroke. The risk is highest for adults newly diagnosed with type 2 diabetes and patients with diabetes who are younger than age 55. African-Americans with diabetes are at even higher risk for stroke at a younger age. Diabetes is a particularly strong risk factor for ischemic stroke, perhaps because of accompanying risk factors, such as obesity and high blood pressure. Diabetes does not appear to increase the risk for hemorrhagic stroke.

Obesity and Metabolic Syndrome

Obesity may increase the risk for both ischemic and hemorrhagic stroke independently of other risk factors that often co-exist with excess weight, including diabetes, high blood pressure, and unhealthy cholesterol level. Weight that is centered around the abdomen (the so-called apple shape) has a particularly high association with stroke, as it does for heart disease, in comparison to weight distributed around hips (pear-shape).

Obesity is particularly hazardous when it is one of the components of metabolic syndrome. This syndrome is diagnosed when three of the following conditions are present: abdominal obesity, low HDL cholesterol, high triglyceride levels, high blood pressure, and insulin resistance. Because metabolic syndrome is a pre-diabetic condition that is significantly associated with heart disease, people with this syndrome are at increased risk for stroke even before diabetes develops.

Other Risk Factors

Migraine. Studies suggest that migraine or severe headache may be a risk factor for stroke in both men and women, especially before age 50. Overall, between 2 - 3% of ischemic strokes occur in people with a history of migraine. However, in patients under age 45, about 15% of all strokes (and 30 - 60% of strokes in young women) are associated with a history of migraines, particularly migraine with aura. For young women with migraines, other risk factors (such as high blood pressure, smoking, and use of estrogen-containing oral contraceptives) may increase stroke risk.

Sickle Cell Disease. People with sickle cell disease are at increased risk for stroke at a young age.

Pregnancy. Pregnancy carries a very small risk for stroke, mostly in women with pregnancy related high blood pressure. The risk appears to be higher in the postpartum (post-delivery) period, perhaps because of the sudden change in circulation and hormone levels.

NSAIDs. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) and diclofenac (Cataflam, Voltaren) may increase the risk of stroke, especially for patients who have other stroke risk factors.