Every three minutes and 27 seconds someone in the UK has a stroke. By the age of 75, one in five women and one in six men will have had one. Strokes are cited by people as one of their four most dreaded conditions. There are many statistics about strokes but an important one became obsolete this week: it used to be said that 80% of them could be prevented.

Research in this week’s Lancet from the Interstroke study says that figure is actually 90%. This latest study, of 26,915 people from 32 countries found that 10 factors accounted for about 90% of the risk of having a stroke. The worst offenders were high blood pressure, lack of exercise, poor diet and smoking. But there was also stress, too much alcohol, heart problems, obesity, diabetes and high cholesterol in hot pursuit.

The study, from McMaster University in Canada, included people who had had strokes caused by either blood clots or bleeding in the brain. The diagnosis was made using clinical criteria for a stroke and a brain scan. Patients or their carers were given a questionnaire asking about risk factors and the results were compared with those of controls (comparable people who hadn’t had a stroke).

The solution

None of these risk factors is new. So why aren’t we doing more, individually, to protect ourselves from strokes? There is always age, and a genetic predisposition to stroke that you are powerless to resist. But the lead author of the paper, Dr Martin O’Donnell, is both realistic and optimistic. “So much of the risk of stroke is modifiable by the individual,” he says. “It’s not just one risk factor, it’s a collection of lifestyle choices – all interlinked. If you exercise and eat well, then you will be a healthy weight and less likely to get diabetes.” O’Donnell knows that people can’t sustain extreme changes of behaviour. But this is fine because in stroke prevention, the risk factors are so connected that even modest changes would add up to a measurably lower risk. An editorial accompanying the paper advises people to eat less salt to reduce the risk of high blood pressure and less sugar and processed food.

“Ideally, healthy behavior should start in youth, but it is never too late and you can do things in moderation,” says O’Donnell. “You should have your blood pressure checked every year.” He admits, though, that prevention is difficult: “It’s not like you wake up one day and say: today is the day I would have had a stroke if I hadn’t taken preventative therapy. But I am a stroke physician and, unfortunately, I am the doctor who sees the patient who didn’t take the blood-pressure tablet.”