Traffic noise linked with the chance of suffering a stroke

The study, involving more than 50,000 people, found that for every 10 decibels increase in noise the risk of having a stroke rises by 14 per cent.

Looking only at those under 65, the chance of a stroke caused by noise was not significant. But in those over 65, the risk increased by 27 per cent for every 10dB increase in traffic noise.

Researchers, who completed the first study to probe links between road traffic noise and stroke, said the findings highlighted the need to tackle exposure to excessive noise.

Scottish campaigners urged vulnerable people to take action regardless of whether or not they lived near a busy road.

Dr Mette Srensen, senior researcher at the Institute of Cancer Epidemiology in Copenhagen, Denmark, who led the research, said: "Our study shows that exposure to road traffic noise seems to increase the risk of stroke.

"Previous studies have linked traffic noise with raised blood pressure and heart attacks, and our study adds to the accumulating evidence that traffic noise may cause a range of cardiovascular diseases. These studies highlight the need for action to reduce people's exposure to noise."

The researchers, writing in the European Heart Journal, examined the medical histories of 51,485 people in Denmark, taking into account other factors which could affect their stroke risk, including smoking, diet and caffeine consumption.

To calculate their road traffic exposure, they used a special noise calculation programme based on data gathered on traffic composition and speed, different types of road and height of buildings in different areas.

The researchers pointed out that the nature of the study meant they could not show road traffic noise was the cause of the increased risk of stroke, only that there was an association.

They also said the mechanism by which noise could increase the risk was still unclear.

Dr Srensen said: "The mechanisms involved are probably the same mechanisms believed to be involved in noise-induced hypertension and heart attacks, namely that noise acts as a stressor and disturbs sleep, which results in increased blood pressure and heart rate, as well as increased level of stress hormones. Taken together, all of these could increase the risk for cardiovascular diseases."

Maddy Halliday, Scotland director at The Stroke Association, said: "Constant loud noise can often increase stress levels which can in turn cause high blood pressure - the single biggest risk factor for stroke.

"This research shows that there could be an indirect link between traffic noise and stroke as a result of increased blood pressure, especially in older people."However 40 per cent of all strokes could be prevented if people took the appropriate action to control their blood pressure.

"So? you could reduce your risk of a stroke by having your blood pressure checked regularly."