Certain conditions can increase your risk of stroke. These are called risk factors. Some are treatable and others are not. Knowing the risk factors can help you avoid a stroke, because treating these conditions is often possible, with lifestyle changes, medicines, or surgery.
Risk Factors That Can Be Treated
High blood pressure (hypertension). High blood pressure is the most important risk factor for stroke. According to the American Heart Association, high blood pressure affects about 1 in 3 American adults. It usually has no symptoms. In fact, most people do not know that they have high blood pressure until they have a stroke or heart attack. Controlling high blood pressure reduces the risk of stroke. Exercise, a healthy diet, and medicines can often control high blood pressure.
Heart disease (such as coronary artery disease, damaged heart valves, heart rhythm problems). People with heart disease have twice the risk of stroke that people with healthy hearts do. Controlling the three major risk factors for heart disease—cigarette/tobacco smoking, high blood cholesterol, and high blood pressure—can also reduce the risk of stroke.
Atherosclerosis. Often called "hardening of the arteries," atherosclerosis is a condition in which fatty materials, cholesterol, and calcium build up on the inside walls of the arteries. This fatty buildup can block vessels.
High red blood cell count. Even a moderate elevation in red blood cell count can be a risk factor for stroke. A high number of red blood cells thickens the blood, leading to blood clots.
Transient ischemic attacks (TIAs). TIAs usually happen when a blood clot temporarily blocks an artery in the brain or neck. This keeps part of the brain from getting the blood it needs. TIAs are a warning sign of a possible stroke. Of those who have had one or more TIAs, more than a third will have a stroke. The symptoms are similar to those of a major stroke. See a doctor right away if you or someone you know has any of the symptoms of a TIA.
Sleep apnea. Sleep apnea is a major risk factor for stroke. Sleep apnea is a condition where people stop breathing (sometimes for up to 10 seconds) while they are in a deep sleep. Sleep apnea increases blood pressure. Studies also show that people with sleep apnea have very low levels of oxygen in the blood, which can cause blood clots to form. If you think you have sleep apnea, you should see your doctor right away.
Patent foramen ovale (PFO). A PFO is an opening between the left and right atria (the upper chambers) of the heart. Everyone has a PFO before birth, but it usually closes shortly after birth. Doctors think that older people who also have a PFO may have a greater risk of stroke, because older people are more likely to develop blood clots in the veins in their legs. These clots could travel in the bloodstream from the legs to the heart. If a person has a PFO, a clot could pass through the opening, from the right side of their heart to the left. From there, the clot may travel to the brain, causing a stroke.
Risk Factors That Cannot Be Changed
Age. The risk of stroke increases with age. From age 55 onward, your chances of having a stroke more than double every ten years.
Gender. The incidence of stroke is about 19% higher for men than for women. Because women in the United States live longer than men, most stroke survivors over 65 are women.
Race. According to the American Heart Association, African Americans have a higher risk of stroke than Caucasians do. This is mainly because African Americans have a higher risk of high blood pressure, diabetes, and obesity.
Diabetes. Although diabetes can be controlled, people with the disease are still more likely to have a stroke. This is mainly because of the circulation problems that diabetes causes. And, if blood sugar is high, brain damage at the time of a stroke may be more severe and widespread. The incidence of stroke is greater for women who have diabetes than for men who have diabetes.
Prior stroke. The risk of stroke increases greatly for a person who has already had a stroke. If a person has had a heart attack, he or she is also at higher risk of having a stroke.
Heredity. The risk of stroke is greater in people who have a family history of stroke and TIAs.
Carotid bruit without symptoms. A bruit (pronounced bru-ee) generally means atherosclerosis is present. A bruit is an abnormal sound heard when a stethoscope is placed over a blocked artery, in this case the carotid artery in the neck. A carotid bruit most often means an increased risk for stroke.
Carotid artery disease. Fatty deposits found in the carotid artery (the main artery between the heart and brain) could block this important blood supply. Depending on the amount of blockage, surgery (carotid endarterectomy) may be performed to remove buildup in the artery.
Contributing Risk Factors
These factors indirectly increase the risk of stroke. Changing lifestyle habits can prevent or greatly lower the risk of stroke.
Smoking. According to the National Stroke Association, smoking doubles the risk for stroke.
Heavy alcohol use. Drinking alcohol is recommended only in moderation. The American Heart Association suggests that moderate intake is an average of one to two drinks per day for men and one drink per day for women. One drink is defined as 1½ fluid ounces (fl oz) of 80-proof spirits (such as bourbon, Scotch, vodka, gin, etc.), 1 fl oz of 100-proof spirits, 4 fl oz of wine, or 12 fl oz of beer. Drinking more than this amount per day increases the risk of high blood pressure and can lead to stroke.
Illegal drug use. Intravenous drug users have a higher risk of stroke. Cocaine use has also been linked to strokes and heart attacks.
Physical inactivity. Inactivity is not only a major risk factor for developing coronary artery disease, but it can also lead to high blood pressure, low levels of high-density lipoproteins (HDL or "good cholesterol"), and diabetes. Exercising 30 to 40 minutes at least 3 to 4 times a week reduces blood pressure, raises HDL, and helps regulate insulin requirements.
Obesity. According to the National Institute of Diabetes and Digestive and Kidney Disease, obesity doubles the risk for developing high blood pressure, a major risk factor for stroke. Many doctors now measure obesity in terms of body mass index (BMI), which is a formula of weight in kilograms divided by height in meters squared (BMI=kg/m2). A person is considered obese if he or she has a BMI of 30 or higher.
Birth control pills (oral contraceptives). Birth control pills alone are a low-level risk factor. But if birth control pills are combined with certain other risk factors, such as smoking, the risk of stroke increases.
See also on this site: Stroke
Updated October 2013