Stroke is a largely preventable disease; its risk factors are well known and many are related to modern lifestyles, writes Victoria Lambert
Whether we’re reading, writing or ruminating, our brains need a constant fresh supply of oxygenated nutrient-rich blood. When that flow is interrupted in any way, we have what some experts call a brain attack. Most people know it as a stroke.
Around 150,000 Britons suffer a stroke every year. Some 85 per cent of strokes are ischaemic, caused by a blocked artery. The other 15 per cent are caused by a bleed in the brain known as a haemorrhagic stroke.
The real frustration for specialists, such as Professor Anthony Rudd, national clinical director for stroke, based at Guy’s and St Thomas’ NHS Foundation Trust, is that many strokes could be prevented through better knowledge of the risk factors.
“The most important risk factor is high blood pressure as it can damage or narrow the arteries,” says Professor Rudd. “If everyone had well controlled blood pressure, below 130mmol/80mmol, it would prevent 60 per cent of strokes.”
He adds: “Smoking is also a significant problem: the toxins in the smoke cause vascular damage and smoking speeds up the rate at which arteries become furred up. The narrower the arteries, the more chance there is of a blood clot causing a blockage.”
Recreational drugs in younger people may be contributory, with ecstasy and amphetamine-type drugs causing surges in blood pressure, which may lead to haemorrhagic stroke
Being diabetic also increases the risk of furred-up arteries, so weight gain, especially around the stomach, which may lead to that condition, is an increasing risk factor partly due to the rise in obesity.
Recreational drugs in younger people may be contributory, Professor Rudd warns, with ecstasy and amphetamine-type drugs causing surges in blood pressure, which may lead to haemorrhagic stroke. Other drugs can cause inflammation in the brain.
“There is no doubt that alcohol increases risk,” he says. “Possibly there is some truth that a little alcohol regularly is good or doesn’t do any harm – a glass of red wine or a beer at night is fine – but don’t save up your weekly units for a Friday night: binge drinking causes huge surges in blood pressure.”
Sleep, or lack of it, is another contributory factor. “If you snore loudly and briefly stop breathing in the night due to sleep apnoea, you have an increased risk of vascular disease and stroke,” he explains.
US researchers from the University of Alabama at Birmingham, who observed 5,666 people for up to three years, reported last year that habitually sleeping less than six hours a night significantly increases the risk of stroke symptoms.
The study’s lead author Megan Ruiter says: “In employed middle-aged to older adults, relatively free of major risk factors for stroke, such as obesity and sleep-disordered breathing, short-sleep duration may exact its own negative influence on stroke development.”
Her team speculated that short-sleep duration is a precursor to other traditional stroke risk factors and, once these traditional stroke risk factors are present, then they may become stronger risk factors than sleep duration alone.
And there are other, perhaps quirky, reasons for stroke too, as BBC broadcaster Andrew Marr demonstrated when he discussed his own stroke recently, claiming it was caused by an energetic session on a rowing machine.
“Very vigorous exercise, the sort that makes your face bright red, like weightlifting, can cause damage to arteries,” says Professor Rudd. “This can also happen to women putting their heads backward into sinks at the hairdresser or to people being spun violently around at a fairground.”
Very vigorous exercise, the sort that makes your face bright red, like weightlifting, can cause damage to arteries
According to the Stroke Association, there are some stroke risks you cannot change. Most people who have strokes are aged over 55 and the risk increases as you get older.
However, more men under 75 have strokes than women, although middle-aged women are more likely to have a stroke than men in the same age group.
Ethnicity matters too. Researchers don’t know why, but people of South Asian, African or African-Caribbean origin are more likely to have a stroke than the rest of the population.
Some of us are born with a congenital risk, such as a hole in the heart called a patent foramen ovale (PFO). This small, flap-like opening allows oxygenated blood from the placenta to bypass the lungs, typically closing shortly after birth.
But when this flap remains open, it can potentially allow dangerous clots to pass from the right side of the heart to the left, travel up to the brain and cause a stroke. “A quarter of us are born with a PFO and more of us with this condition have a stroke than not,” says Professor Rudd.
A particular problem within the heart is atrial fibrillation (AF), the most common cardiac arrhythmia or irregular heartbeat. Professor John Camm, professor of clinical cardiology at St George’s, University of London and current president of the Arrhythmia Alliance, says AF accounts for 15 per cent of all strokes.
“When AF occurs, the upper chambers of the heart don’t function properly. They try to pump far too fast – 600 times a minute. You’d have to be the size and weight of an insect wing to be able to do that,” he says. “Instead, the chambers of the heart look like a bag of worms squirming, blood becomes static and doesn’t move properly and clots form.” These clots can break off and fly around the circulation, obstructing arteries leading to the brain.
AF is usually due to ageing, but can also be caused by cardiovascular disease. Worryingly, it is often a silent condition, with many not knowing they have it until the day they suffer a stroke, and these types of events are large and more often fatal, warns Professor Camm.
Yet, there are practical treatments for both AF and PFO. For the latter, occluding devices are proving to be very effective, literally closing the gap in the heart. With AF, drugs or a procedure called catheter ablation can get the heart back into a normal rhythm, he says.
During ablation, several flexible catheters are introduced into the patient’s blood vessels and pushed towards the heart. Local heating or freezing is used to destroy the abnormal tissue causing the heart rhythm disturbance.
Lifestyle changes, which ought to be easy, seem more difficult for the public to take on board. This could be partly to do with myths, such as strokes “can’t happen to younger people”. Yet Professor Rudd says younger people are not immune, having seen a 25 year old in his clinic recently.
Another myth Professor Rudd hears is that it is OK to smoke for a long time before the danger becomes real. “The risk increases as soon as you start,” he says, “but as soon as you stop, the risk comes down very, very quickly. Within a year or two, your risk is no higher than a non-smoker; even the day you stop, the risk falls.
“Stroke is a really horrible condition: once the brain is damaged, it can’t repair itself. You can recover, but you cannot repair a hole in the middle of the brain.
“People think: ‘Oh you’ve got to die of something’. But stroke is largely preventable and it cuts lives short, and ends people’s ambitions for the rest of their life when they do survive.”
WHAT DOES A STROKE LOOK LIKE?
- Inside the arteries, the flow of blood is interrupted by a blockage – a clot of blood cells has jammed an artery
- The area of the brain relying on blood is immediately starved
- Within moments, the area of brain cells affected begins to die, even while other local capillaries try desperately to divert blood to the stricken area
- Perhaps an artery has burst, haemorrhaging blood cells which die rather than reach the area of brain tissue expecting them
- If the blood is not helped to flow again, through the use of clot-busting drugs, or the bleeding is not stopped and swelling relieved, then damage may be permanent causing disability
- Our brains are divided into regions from where different functions, such as speech or movement, are controlled – with the right half of the brain controlling the left side of the body and vice versa
- So as the cells begin to die off, in minutes messages to different parts of the body stop being processed via neurotransmitters
- The tiny muscles and nerves which support the face may be the first to lose instruction
- They stop working, and the facial skin sags and feels prickly, then numb
- If the area affected is where we process speech and language, then talking becomes a problem; but any of the senses may be affected
- As the area of dead cells spreads in the brain, areas of the body further away from the brain quickly begin to be affected
- The arm on the opposite side of the body to the area of cell death may become weak and numb; the legs may not hold you up or propel you forward
HIGH BLOOD PRESSURE
People with high blood pressure may not have any symptoms, so it is important to check your blood pressure regularly. Your doctor can prescribe medication to help with conditions that increase the risk of stroke, including high blood pressure, heart disease, diabetes, high cholesterol and irregular heartbeat. But a healthy diet and regular exercise are important.
Atrial fibrillation (AF) is a type of irregular heartbeat, affecting around 800,000 people in the UK. Symptoms include palpitations (being aware of your heart beating fast), breathlessness, chest pain, fatigue; or you may have no symptoms, but an irregular pulse. A doctor or nurse will need to run tests, including a 24-hour heart monitor, to find out if you have AF.
Drinking too much alcohol increases your blood pressure. Binge drinking, (more than six units of alcohol within six hours), can cause your blood pressure to increase rapidly which greatly increases the risk of stroke. Don’t drink every day or exceed the recommended limits (for women no more than two to three units a day; for men no more than three to four units).
You are twice as likely to have a stroke if you smoke. Ask your GP to refer you to a stop smoking group or try self-help books for advice. Nicotine replacement chewing gum, sprays and patches can help, but may not be suitable for people who have already had a stroke.
Eating your five a day and having plenty of fibre can reduce your stroke risk. But high-fat foods can raise your cholesterol and a lot of salt in your food can cause high blood pressure, the biggest risk factor for stroke. Cut down on salt, (check food labels on pre-prepared meals for “hidden” salt). Keep a food diary and use smaller plates to control your portion sizes.
LACK OF EXERCISE
Regular physical activity lowers your blood pressure, helps balance fats in your body and improves your ability to handle insulin. Plan to exercise at least 30 minutes, five days a week, but build up slowly. Warm up and cool down with several gentle stretching exercises, important for letting your heart rate return to normal after exercise.