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Road traffic noise ups risk of stroke

Road traffic noise ups risk of stroke Older people most at risk

Exposure to noise from road traffic can increase the risk of stroke, particularly in the over-65s, a new study has found.

For every 10 decibels more noise, the risk of having a stroke increased by 14 per cent overall, and 27 per cent in the over-65s.

Study leader Dr Mette Sørensen, senior researcher at the Institute of Cancer Epidemiology in Copenhagen, 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."

The study involved 57,053 men and women aged between 50 and 64, in the Copenhagen and Aarhus areas between 1993 and 1997 who were tracked for an average of ten years. Some 1,881 participants suffered a stroke during this time.

The study participants were exposed to noise levels ranging from 40 - 82dB. More than a third were exposed to noise levels greater than 60dB.

The link between stroke risk and noise level seemed to be particularly strong in older people. For people under 65 years of age, there was no statistically significant increased risk of stroke, the researchers said.

However, the risk increased by 27 per cent for every 10dB of higher road traffic noise in those aged 65 years and over. The findings also suggested "a threshold limit" at approximately 60dB, above which the risk for stroke seemed to increase further.

"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," Dr Sørensen said.

How road traffic noise is linked to an increased risk of stroke and heart disease is unclear but Dr Sørensen suggested it may be related to disturbed sleep patterns.

She 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.

"In addition, older people tend to have more fragmented sleep patterns and are more susceptible to sleep disturbances. This could explain why the association between road traffic noise and risk of stroke was seen mainly in the oldest participants."

This article was published on Wed 26 January 2011



Image © Sergiy Serdyuk - Fotolia.com


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