H- Risk Factors for Strokes:
H1- High blood pressure:
The top risk factors for thrombotic strokes are the presence of hypertension, atherosclerosis, excessive blood-clotting factors (such as homocysteine, fibrinogen, and LDL cholesterol), heart valve defects, diabetes, and aging.
High blood pressure is the most prominent risk factor for stroke. In fact, stroke risk varies directly with blood pressure. Many people believe the effective treatment of high blood pressure is a key reason for the accelerated decline in the death rates for strokes.
H2- Mid-Life Blood Pressure:a New Risk Factor for Stroke
A 30-year study of male twins showed that elevated blood pressure in mid-life predisposed men to accelerated brain aging and an increase in strokes later in life. Men with even mildly elevated blood pressure 25 years before showed smaller brain volumes and more strokes compared to their twin brothers who did not have the elevation in blood pressure. This study, published in the 1999 Journal of Stroke, emphasized the importance of aggressively treating elevated blood pressure even if it is not grossly abnormal[1]
H3- Increasing age:
The chance of having a stroke more than doubles for each decade of life after age 55. while strokes are common among the elderly, substantial numbers of people less than 65 also have strokes.
“One of the most significant stroke risk factors is advanced age. 95% of strokes occur in people age 45 and older (Senelick, Rossi, Dougherty 1994), and two-thirds of strokes occur in those over the age of 65 (NINDS 1999, Senelick et al., 1994). A person's risk of dying if he or she does have a stroke also increases with age. “However, stroke can occur at any age, including in fetuses.”[2]
H4- Gender
Overall, men have about a 19% greater chance of a stroke than women. Among people under age 65, the risk for men is even greater when compared to that of women.
Some risk factors for stroke apply only to women. Primary among these are pregnancy, childbirth, menopause and the treatment thereof..
H5- Heredity (family history) and race.
The chance of a stroke is greater in people who have a family history of strokes. African-Americans have a much higher risk of death and disability from a stroke than aucasians, in part because African-Americans have a greater incidence of high blood pressure.
H6- Prior stroke
The risk of a stroke for someone who has already had one is several times that of a person who has not.
H7- Smoking
In recent years studies have shown cigarette smoking to be an important risk factor for stroke. The nicotine and carbon monoxide in cigarette smoke damage the cardiovascular system in many ways. The use of oral contraceptives combined with cigarette smoking also greatly increases stroke risk.
H8- Excessive alcohol intake:
Excessive drinking (an average of more than 1 drink per day for women and more than 2 drinks per day for men) and binge drinking can raise blood pressure; contribute to obesity, high triglycerides, cancer, and other diseases; and cause heart failure, leading to stroke.
H9- Certain kinds of drug “abuse”
Intravenous drug abuse carries a high risk of stroke from cerebral embolisms. Cocaine use has been closely related to strokes, heart attacks, and a variety of other cardiovascular complications. Some of them have been fatal even in first-time cocaine users.
H10- Diabetes mellitus
Diabetes is an independent risk factor for stroke and is strongly correlated with high blood pressure. While diabetes is treatable, having it still increases a person's risk of a stroke. People with diabetes often also have high cholesterol and are overweight, increasing their risk even more.
H11- Carotid artery disease
The carotid arteries in your neck supply blood to your brain. A carotid artery damaged by atherosclerosis (a fatty buildup of plaque in the artery wall) may become blocked by a blood clot, which may result in a stroke. If you have a diseased carotid artery, your health care provider may hear an abnormal sound in your neck, called a bruit, when listening with a stethoscope.
H12- Heart disease
A diseased heart increases the risk of a stroke. In fact, people with heart problems have more than twice the risk of a stroke as those with hearts that work normally. Atrial fibrillation (the rapid, uncoordinated beating of the heart's upper chambers), in particular, raises the risk for stroke. Heart attack is also the major cause of death among survivors of a stroke.
H13- Transient ischemic attacks (TIAs).
TIAs are "mini-strokes" that produce stroke-like symptoms, but no lasting damage. They are strong predictors of a stroke. A person who has had one or more TIAs is almost 10 times more likely to have a stroke than someone of the same age and sex who hasn't.TIAs are extremely important stroke warning signs.
H14- High red blood cell count
A moderate or marked increase in the red blood cell count is a risk factor for stroke. The reason is that more red blood cells thicken the blood and make clots more likely.
H15- Sickle cell anemia Which can cause blood cells to clump up and block blood vessels, also Increases stroke risk. Stroke is the second leading killer of people under 20 who suffer from sickle-cell anemia.
H16- Heart disease risk factors related to stroke
Other secondary risk factors for a stroke are caused by increasing the risk of heart disease. These indirect factors include high blood cholesterol and lipids, physical inactivity, and obesity.
Other potential risk factors for stroke are:
1- Geographic location
Stroke is more common in the southeastern United States than in other areas. These are the so-called "stroke belt" states. The age-adjusted death rates from a stroke are much higher inthese states than in the rest of the country.
2- Air pollution
There is one study, which establishes link between air pollution, ischemic strokes. Even this study does not have any conclusion about what mechanism, or what trigger factors lead to cardiac problem, and then cause stroke, but the researchers, who are from Beth Israel Deaconess Medical Center state: “That pollution can cause changes in coaguable states [blood clotting abilities]." The following is their report on October 31, 2005[3]
“The risk of ischemic stroke - which results when a blood clot travels to the brain - increases with a rise in particulate air pollution, according to a study in Stroke: Journal of the American Heart Association. Led by researchers at BethIsraelDeaconessMedicalCenter (BIDMC) and the Harvard School of Public Health (HSPH), the findings are described in the October 27, 2005 on-line rapid access issue of the journal.
The study, which examined the air quality on a total of 37,000 days in nine separate cities, found that risk of hospitalization for ischemic stroke was one percent higher on days with relatively high levels of air pollution, compared with low-air pollution days, according to lead author Gregory Wellenius, Sc.D., postdoctoral fellow in cardiology at BIDMC.
"Although these effects sound relatively small, given the large number of people exposed to air pollution and the large number of people at risk for stroke, from a public-health perspective the actual number of strokes [we're talking about] could be significant," says Wellenius. Stroke is the third leading cause of death in the U.S., affecting more than 700,000 individuals each year.
Previous work by Wellenius and coauthors Murray Mittleman, MD, DrPH, of BIDMC's Cardiovascular Epidemiology Research Unit and Joel Schwartz, PhD, of HSPH had established a "consistent increased risk" for cardiac health problems associated with exposure to ambient air particles.
"Air pollution has been shown to trigger heart attacks and to aggravate the conditions of patients with congestive heart failure," says Mittleman, who is also Associate Professor of Medicine at HarvardMedicalSchool. "These new findings, demonstrating that incidence of clot-based strokes also increase, is in keeping with our earlier data showing a relationship between air pollution and heart and lung disorders."
(The study also looked at the incidence of hemorrhagic stroke, which is caused by bleeding in the brain, during the same "high pollution" days, notes Wellenius, but found no association between the two.)
The air pollution in question - particulate matter smaller than 10 micrometer in diameter - includes particles from car and truck exhaust, power plants and refineries. The measurements were provided by the U.S. Environmental Protection Agency from nine U.S. cities including Birmingham, Ala., Chicago, New Haven, Conn., Cleveland, Detroit, Minneapolis, Pittsburgh, Salt Lake City and Seattle.
The authors analyzed hospital admissions among Medicare patients who represented an average age of79. Seventy-five percent of the patients were white and 61 percent were female. Their findings showed that during the course of their study, there were 155,503 hospital admissions for ischemic stroke. The final analysis demonstrated a 1.03 percent rise in ischemic stroke on the days with the highest pollution measures.
"We don't know exactly what mechanisms are involved that trigger these cardiac events”, says Wellenius. "However, we do know that particulates in the air promote inflammation, which is a significant risk factor for cardiac events; that exposure to particulates can lead to changes in heart rate and blood pressure; and that pollution can cause changes in coaguable states [blood clotting abilities]."
The authors say that future research will focus on finding out which pollutants are most toxic, and which patients are at greatest risk for health problems stemming from air pollution.”
3-Season and Climate: Stroke deaths occur more often during periods of extremely hot or cold temperatures.
4- Socioeconomic factors:
There is some evidence that people of lower income and educational levels have a higher risk for stroke.
[1] “Risk Factors of Stroke”. The National Stroke Association. 03-12-2006.
[2] “Stroke” en.wikipedia.org 03-01-2006. 03-14-2006.
[3]“Study establishes link between air pollution, ischemic strokes”. Bright Surf.com.10-31-2005.
BethIsraelDeaconessMedicalCenter. 03-25-2006.