Is suffering a stroke something that is largely beyond our control, or can we take steps to dramatically reduce our risk? Here are some striking answers.
What is a stroke?
A stroke involves damage to the brain in which something has gone wrong with the circulation. There are two types of stroke.
The most common, ischemic stroke, accounts for about 80 per cent of strokes and occurs when blood flow to the brain is reduced or, more likely, blocked altogether.
This can be caused by atherosclerosis (hardening of the arteries) that results from high cholesterol or high blood pressure; or by a blood clot from the heart that blocks off an artery feeding the brain.
In the second type, hemorrhagic stroke, a rupture of blood vessels in the brain results in bleeding in the brain. This injures brain tissue and kills cells known as neurons.
What are the effects of a stroke?
The impact of a stroke depends on the part of the brain that is injured and the severity of the stroke. It can affect a person’s ability to move, read, write, see, speak, remember and think.
How common are strokes?
Approximately 50,000 Canadians are hospitalized each year because of strokes (all types); more than 14,000 die as a result of them. Stroke is the third leading cause of death in Canada, and the leading cause of disability in North America.
The Heart and Stroke Foundation reports that of every 100 Canadians who have a stroke, 40 are left with a moderate to severe impairment and 10 are so severely disabled that they require long-term care.
What is the burden of a stroke?
For the patient, the emotional toll of experiencing a stroke can be tremendous in terms of reduced daily functioning and loss of independence; and for the caregivers, the burden is daunting.
On the financial front, health-care costs in just the first six months following a stroke amount to more than $2.5 billion a year in Canada, according to a study presented in June at the Canadian Stroke Congress.
What are the risk factors for strokes?
Non-modifiable risk factors for stroke — those over which people have no control — are family history, ethnicity (African-Americans are among the higher-risk groups), age and gender. Strokes are more common in men, and the risk of having a stroke increases with age.
Modifiable (or lifestyle-related) factors have traditionally included diet, obesity, smoking, stress, diabetes, physical inactivity, high blood pressure and high cholesterol.
The study: O’Donnell and the Interstroke investigators. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the Interstroke study): a case-control study. The Lancet, published online June 18.
What was this study about?
The Interstroke study was the most ambitious research project undertaken to identify, on a global scale, the major risk factors for stroke. Conducted in 22 countries over a three-year period, this study enrolled 3,000 victims of stroke and compared them with 3,000 very similar subjects who had not had a stroke.
By obtaining detailed information on both healthy and unhealthy habits and characteristics of all the participants, the authors of this study were able to determine in a quantitative way which factors contribute most significantly to stroke risk.
What were the results of the study?
In general terms, the study concluded that an astounding 90 per cent of the risk for both types of stroke comes from 10 risk factors.
In other words, these 10 ingredients account for 90 per cent of the global burden of this disease. Moreover, the majority of these factors fall either partially or completely under our control.
So what increases my risk for stroke?
Far and away, the greatest culprit lies in high blood pressure (or hypertension), which alone accounts for over one-third of the total risk for stroke around the world.
Not surprisingly, higher levels, such as those consistently greater than 160/90, are associated with the greatest risk. Rounding out the top five are smoking, abdominal obesity, a diet high in saturated fats and salt, and a lack of physical activity.
The next five most important risk factors include diabetes, alcohol consumption of more than 30 drinks per month (or binge drinking), psychological and social factors in the form of stress and depression, heart arrhythmias, and finally, novel blood proteins associated with storing and transporting fat in the body.
Interestingly, unlike with heart attacks, cholesterol levels did not appear to be predictive of strokes.
What can we do with this information?
The importance of a healthy diet and regular exercise for stroke prevention will come as no surprise to anyone who has not been living in a cave for the past 40 years, but Interstroke reminds us of the critical role that high blood pressure plays in this picture.
If you’re over the age of 30, you need to know what your blood pressure is, and if it’s elevated, you need to seek medical attention.
As for the other risk factors, it may be something of a leap of faith to conclude that controlling them will dramatically reduce the possibility of having a stroke. However, the fallout associated with ignoring your cardiovascular risk profile is simply too dangerous to accept.
The material provided in HealthWatch is designed for general educational purposes only and does not pertain to individual cases. It should not replace necessary medical consultations with your own doctor or medical professional.