London: Over exposure to noise from road traffic may increase the risk of stroke, particularly among older individuals, a new study has claimed.The study, which examined the link between road traffic noise and stroke in more than 51,000 Danish people, found that the risk of stroke increased by 14 per cent for every 10 decibel increase in noise level.
And the risk increased 27 per cent among those who are over 65 years, found the study by researchers at the Institute of Cancer Epidemiology in Copenhagen, Denmark.
The researchers said that they had accounted for air pollution and other factors like differences in lifestyle, meaning they believed there was a genuine association between noise and stroke risk.
Dr Mette Sorensen, 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," Dr Sorensen said.
For their study, the researchers analysed data from Danish citizens, aged between 50 and 64 year, who participated a lifestyle survey conducted between 1993 and 1997.
They examined the medical histories and residential addresses of the participants and after following them for about a decade, the researchers found that a total of 1,881 suffered a stroke during the study period.
The participants lived in homes with estimated noise levels ranging from 40dB -- the sound of a quiet conversation to 82dB -- that of a busy street.
For older people, there appeared to be a step-change in their risk of stroke at about 60dB, the researchers found.
Dr Sorensen said about one in five strokes in urban areas could be due to living in noisy homes.
He said: "If we assume that our findings represent the true risk, and the association between traffic noise and stroke is causal, then an estimated eight percent of all stroke cases, and 19 per cent of cases in those aged over 65, could be attributed to road traffic noise."
He emphasised that the study only looked at urban homes, which were likely to be noisier than rural ones, and that it could not prove that noise itself was a causal factor in stroke risk.
Exposure to noise is thought to increase blood pressure and cause changes in levels of stress hormones, which may contribute to the increased risk of stroke. In addition, exposure to traffic noise may also lead to sleep disturbances, which can contribute to stroke risk, the researchers said.
The study is published in the journal European Heart Journal.
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