Long-Term Exposure to Road Traffic Noise Linked to Higher Parkinson's Disease Risk

Long-term exposure to residential road traffic noise may slightly increase the risk of developing Parkinson's disease, according to a large Danish study published in JAMA Neurology.

Traffic noise has long been recognized as a public health concern due to its links with cardiovascular disease, hypertension, sleep disturbances, mental health problems, and impaired cognitive development in children. The new findings suggest it may also contribute to the risk of neurodegenerative disorders.

Researchers followed more than 3 million Danish residents aged 40 years and older for nearly 18 years. During the study period, 20,587 participants were diagnosed with Parkinson's disease.

Using Denmark's nationwide address and health registries, the investigators estimated road traffic noise exposure at every residential address since 1990. Noise levels were calculated for both the most exposed (street-facing) and least exposed (quiet) sides of each home, and a rolling 10-year average was determined for every participant, even if they changed residence. The analysis also accounted for factors such as age, sex, socioeconomic status, and air pollution.

The study found that higher long-term exposure to road traffic noise was associated with a modest increase in Parkinson's disease risk. Every 11.5-decibel increase in noise on the most exposed side of a home was linked to a 3% higher risk of Parkinson's disease. On the quieter side of the home, where bedrooms are often located, every 8.9-decibel increase in noise was associated with a 4% increase in risk.

The researchers also found evidence that a quieter home environment may offer some protection. Among people exposed to road traffic noise levels above 50 decibels, those whose homes had a quiet side that was at least 10 decibels quieter than the street-facing side had a lower risk of developing Parkinson's disease.

Although the study does not establish a cause-and-effect relationship, the authors suggest that chronic traffic noise may contribute to neurodegeneration by disrupting sleep and triggering long-term stress and inflammatory responses, mechanisms that have previously been linked to the loss of dopamine-producing neurons characteristic of Parkinson's disease.

The researchers conclude that residential traffic noise may represent a previously underrecognized environmental risk factor for Parkinson's disease. They note that reducing long-term noise exposure—through urban planning measures such as locating bedrooms and living spaces away from busy roads—could become an important strategy for protecting brain health as the population ages.

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