Long-term exposure to road traffic noise may increase the risk of developing Parkinson's disease, a large new study has suggested. Researchers followed more than 3 million adults for nearly two decades and found a modest but consistent link between traffic noise levels and the neurodegenerative disorder.
The findings, published in JAMA Neurology, indicate that even small increases in noise exposure were associated with a higher risk. This connection persisted even after accounting for other potential factors such as air pollution, access to green space, income, and education levels.
Parkinson's disease affects approximately 1.1 million Americans, with nearly 90,000 new diagnoses each year. Projections indicate that these numbers are expected to rise as the global population ages, underscoring the urgency to identify modifiable risk factors.
The disorder is characterized by the progressive loss of dopamine-producing nerve cells, which are crucial for controlling movement. This degeneration leads to symptoms including tremors, slowed movement, muscle rigidity, and balance problems. Non-motor symptoms, such as sleep disturbances, depression, and cognitive decline, are also associated with Parkinson's.
While the study did not establish a direct causal relationship between noise and Parkinson's, experts view the research as adding to a growing body of evidence that chronic environmental noise poses a significant public health threat. "Exposure to chronic noise is still a young entrant in the Parkinson’s disease risk-factor literature," said study co-author Thomas Munzel, an environmental cardiologist at the University Medical Center Mainz in Germany, suggesting that more research is needed.
Previous studies, including research from 2025, have explored the potential impact of loud noises, with some studies showing motor deficits in mice with brains altered to mimic Parkinson's disease. Several smaller human studies have also indicated a relationship between traffic noise and the disorder. The current study, however, distinguishes itself through its considerably larger dataset and its comprehensive analysis of confounding variables.
For this study, researchers analyzed Parkinson's disease diagnoses among participants between 2000 and 2017. Nearly 20,600 individuals were diagnosed with the disease during this period. The team then assessed traffic noise levels at the loudest and quietest points within the participants' homes.
Results indicated that for every 11.5-decibel increase in traffic noise at the loudest point in a home—a level only slightly louder than normal breathing—the risk of developing Parkinson's disease rose by three percent. On the side of participants' homes least exposed to sound, every 9-decibel increase in noise was associated with a four percent increase in the risk of the condition.
Experts not involved in the research noted in an accompanying editorial that these findings suggest "road traffic noise may be a novel environmental risk factor for [Parkinson’s]."
Additionally, the study suggested that a person's sleeping location within their home might play a role. Individuals whose homes exhibited a significant difference between the noisiest and quietest sides had a lower risk, even if the front of their house was exposed to considerable noise.
Although the study authors did not explicitly propose a mechanism for the association, prior research offers potential explanations. Disruptive sounds are known to interrupt sleep and can trigger a stress response, leading to the production of molecules that may cause cellular damage in the brain, potentially contributing to disease development. Neurobiologist Jannette Rodríguez Pallares, who was not involved in the research, commented in the editorial that while it is unlikely noise directly causes nerve cell death, "it may impair the brain’s protective mechanisms and promote biological processes involved in disease development."