Living in areas with persistent road traffic noise could increase the likelihood of developing Parkinson’s disease, according to a new study by Danish researchers. The survey, which tracked more than three million people aged 40 and older over an 18-year period, was published in «JAMA Neurology.»
Parkinson’s disease is the world’s second most common neurodegenerative disorder, affecting more than 8.5 million people. While certain risk factors, such as genetics and aging, cannot be changed, scientists continue to explore environmental factors that may contribute to the disease and could potentially be reduced.
How the study was carried out
To assess long-term exposure to traffic noise, the researchers did not rely on participants’ own estimates of how noisy their homes were. Instead, they used a validated noise prediction model to calculate traffic noise levels at every residential address dating back to 1990.
The model estimated sound levels on both the side of each home facing the road, where noise is typically highest, and the quieter side, which often overlooks a courtyard or backyard. A rolling 10-year average was then calculated for each participant, taking into account any changes of residence during that period.
The team identified Parkinson’s disease cases using records from the Danish National Patient Registry. To minimize the influence of other factors, the analysis also accounted for age, sex, household income and exposure to air pollution.
What the researchers found
The results revealed a consistent association between long-term traffic noise exposure and a higher risk of Parkinson’s disease.
According to the study, every 11.5-decibel increase in traffic noise on the most exposed side of a home was linked to a 3% increase in the risk of developing Parkinson’s disease. On the quieter side of the residence, each 8.9-decibel rise in noise was associated with a 4% increase in risk.
The researchers also found evidence that having access to a quieter part of the home may be beneficial. Among people exposed to traffic noise levels above 50 decibels, those whose homes had at least a 10-decibel difference between the quietest and noisiest sides showed a lower risk of Parkinson’s disease.
Implications for housing and urban planning
The findings suggest that long-term exposure to residential traffic noise may be an environmental factor linked to Parkinson’s disease, in addition to being a source of everyday discomfort.
The researchers say the results could help guide future urban planning and residential design. Measures such as placing bedrooms and main living areas on the quieter side of buildings, or incorporating designs that reduce traffic noise, may help limit residents’ long-term exposure.
