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Road traffic noise tied to higher stroke risk in older adults

Kathleen Blanchard's picture

Road traffic is linked to increased chance of having a stroke that increases for every 10 decibels of noise

According to study findings, traffic noise can up stroke risk especially for those over age 65. According to a study finding, the risk increases 27 percent for every 10 decibels of road traffic.

In the study, Danish researchers at the Institute of Cancer Epidemiology, Danish Cancer Society in Copenhagen, Denmark note the findings point to the need to lower people's exposure to road noise. Past studies have linked traffic noise to increases in blood pressure and cardiovascular disease. For individuals over age 65, the scientists found a threshold of 60 decibels that seemed to increase the chances of stroke even further.

The scientists note, "This is the first study ever to investigate the association between exposure to road traffic noise and risk of stroke, and, therefore, more research is needed before any firm conclusions can be made."

In the study, researchers looked at stroke rates among 57,053 people aged between 50 and 64, in the Copenhagen and Aarhus areas between 1993 and 1997 who participated in the Danish "Diet, Cancer, and Health" cohort study.

Demographic information was available for 51,485 of those enrolled. The group was followed for ten years. During the study, 1,881 suffered a stroke.

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Noise exposure ranged from 40dB to 82dB. At the beginning of the study, 35% of people were exposed to noise levels higher than 60dB.

The researchers took into account a wide range of variables to discover traffic noise may increase stroke risk for those over age 65, including lifestyle factors like smoking, diet, alcohol consumption and caffeine intake. The program also noted distance from the road, position of the study participant's homes, road and traffic type, as well as traffic speed.

Dr Sørensen 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% of cases in those aged over 65, could be attributed to road traffic noise. She also notes the stud does not show traffic noise causes stroke, only an association.

Traffic noise likely increases stress hormones, heart rate and blood pressure, leading to higher risk of cardiovascular disease and stroke says Dr Sørensen. It may be that the link was found in older individuals because they are more susceptible to disrupted sleep patterns.

The authors say, "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 link found between higher stroke risk from road traffic noise needs further investigation, and may occur from the same factors that lead to noise induced hypertension and heart attack, suggest the researchers.

European Heart Journal. doi:10.1093/eurheartj/ehq466