A large-scale Danish study has found that prolonged exposure to road traffic noise is linked to an increased risk of developing Parkinson’s disease. The research, published in JAMA Neurology, is the most extensive investigation on this topic to date, tracking over 3.1 million adults aged 40 and above for 18 years using nationwide health registry data.
The study measured noise exposure at participants’ residences, comparing sound levels between the most and least exposed sides of each home. Results indicated a modest but consistent increase in Parkinson’s risk, with a 3% rise associated with every 11.5-decibel increase in noise at the loudest facade. The presence of quieter areas within the home appeared to mitigate this effect, suggesting that some degree of noise shielding may reduce the potential impact.
The researchers accounted for air pollution in their analysis and examined socioeconomic indicators such as education and income. They contend that lifestyle factors—though not directly measured—are unlikely to explain the association, given the consistent link observed across different demographic groups. Previous studies have connected environmental toxins to neurological disorders, but this investigation is among the first to associate noise pollution with the risk of Parkinson’s disease.
Biological pathways that might underlie the connection include chronic stress responses and disrupted sleep caused by persistent noise exposure. Elevated levels of the stress hormone cortisol, triggered by sleep disturbances, may contribute to the development of neurological conditions like Parkinson’s.
Experts not involved in the study have noted that while the findings are not surprising, they highlight important nuances in environmental noise exposure. Dr. Peter Chan, a senior researcher in environmental epidemiology, emphasized the significance of differences in noise levels within the same home, suggesting potential mitigation by choosing quieter living spaces. However, he cautioned that disentangling the effects of noise from other risk factors related to socioeconomic status remains challenging.
John Stewart, chair of the UK Noise Association, remarked that the research adds to mounting evidence linking traffic noise to adverse physical and mental health outcomes. He pointed out that the strongest associations were observed near main roads, where noise levels are highest.
Environmental noise pollution affects nearly a third of Europeans, often exceeding World Health Organization recommended limits. The study’s lead author, Thomas Münzel, described environmental noise as an emerging but credible risk factor for Parkinson’s disease, calling for further investigation to better understand its role in neurological health.