Could you please be quiet, please?

Around 18 percent of the UK general population may have misophonia – a decreased tolerance to certain sounds – according to a study written by Silia Vitoratou and colleagues from King’s College in London and published in the open-access journal PLOS ONE.

People with misophonia have strong negative reactions when hearing certain common sounds, such as chewing or sniffing. There’s little research on the prevalence of misophonia in a general population, though previous studies have reported estimates ranging from 5-20 percent within specific samples, such as university students.

Here, the authors surveyed 768 people as a sample representative of the UK general population with a mean age of 46.4. 13.6 percent of the sample was aware of the term misophonia prior to the survey, with 2.3 percent self-identifying as having misophonia.

The authors’ survey asked about common “trigger sounds” and asked respondents to describe their emotional response and its intensity using a 10-point scale. The authors also asked people about how these sounds affect their life, the way they see themselves, their personal and professional relationships.

They conducted interviews with 26 self-identified individuals with misophonia and 29 individuals from the general survey pool to establish a cut-off score for significant symptoms of misophonia. The new questionnaire allows researchers and clinicians to measure these aspects of misophonia and see how things change over time.

The authors found that 18 percent of their sample appeared to have significant symptoms of misophonia, which can include feeling trapped or helpless around these sounds, as well as blaming yourself for the strong reactions and missing out on things because of the impact of sounds.

Furthermore, the most common negative reaction to these sounds in the general population was irritation, while the individuals with misophonia reported that they felt trapped or helpless when they could not get away from these sounds. While there were no significant differences in the prevalence of misophonia based on gender, the authors found individuals above the threshold for misophonia were an average 3.3 years younger than those below the threshold, a small but significant difference.

Silia Vitoratou noted “Ιt is important that our study revealed that 1 in 5 people in the UK experiences significant misophonic reactions, but only a small fraction was aware of the term.  This means that most people with misophonia do not have a name to describe what they are experiencing. Our team works hard to raise the condition’s profile and to provide clinicians with the tools they need to understand and assess misophonia effectively.”

Jane Gregory from the University of Oxford, UK, adds: “Our survey captured the complexity of the condition. Misophonia is more than just being annoyed by certain sounds, it’s about feeling trapped or helpless when you can’t get away from these sounds and missing out on things because of this.

“It’s about feeling like there’s something wrong with you for the way you react to sounds, but also not being able to do anything about it. It can be such a relief to find out that you are not alone, that other people react this way to sounds too. To find out that there is a word for what you are experiencing.”

Road Noise and Hypertension

Constant noise can also have physical as well as psychological effects.  If you live near a busy road you might feel like the constant sound of roaring engines, honking horns and wailing sirens makes your blood pressure rise and now a new study published in JACC: Advances confirms it can do exactly that.

Previous studies have shown a connection between noisy road traffic and increased risk of hypertension. However, strong evidence was lacking, and it was unclear whether noise or air pollution played a bigger role. The new research shows that it is exposure to road traffic noise itself that can elevate hypertension risk.

“We were a little surprised that the association between road traffic noise and hypertension was robust even after adjustment for air pollution,” said Jing Huang, assistant professor in the Department of Occupational and Environmental Health Sciences in the School of Public Health at Peking University in Beijing, China, and lead author of the study.

Previous studies of the issue were cross-sectional, meaning they showed that traffic noise and hypertension were linked, but failed to show a causal relationship. For the new paper, researchers conducted a prospective study using UK Biobank data that looked at health outcomes over time.

Researchers analyzed data from more than 240,000 people (aged 40 to 69 years) who started out without hypertension. They estimated road traffic noise based on residential address and the Common Noise Assessment Method, a European modeling tool.

Using follow-up data over a median 8.1 years, they looked at how many people developed hypertension. Not only did they find that people living near road traffic noise were more likely to develop hypertension, they also found that risk increased in tandem with the noise “dose.”

These associations held true even when researchers adjusted for exposure to fine particles and nitrogen dioxide. However, people who had high exposure to both traffic noise and air pollution had the highest hypertension risk, showing that air pollution plays a role as well.

“Road traffic noise and traffic-related air pollution coexist around us,” Huang said. “It is essential to explore the independent effects of road traffic noise, rather than the total environment.”

The findings can support public health measures because they confirm that exposure to road traffic noise is harmful to our blood pressure, she said. Policymaking may alleviate the adverse impacts of road traffic noise as a societal effort, such as setting stricter noise guideline and enforcement, improving road conditions and urban design, and investing advanced technology on quieter vehicles.

“To date, this is the first large-sized prospective study directly addressing the effect of road traffic noise on the incidence of newly-diagnosed hypertension,” said Jiandong Zhang, cardiovascular disease fellow in the division of cardiology at the University of North Carolina at Chapel Hill, and author of the accompanying editorial comment. “The data demonstrated in this article provides a higher quality of evidence to justify the potential to modify road traffic noise and air pollution from both individual and societal levels in improving cardiovascular health.”

As a follow-up, Huang said field studies are underway to better understand the pathophysiological mechanisms through which road noise affects hypertension.

The study was supervised by Kazem Rahimi, lead of the Deep Medicine program at the Nuffield Department of Women’s and Reproductive Health at the University of Oxford, and Samuel Cai, lecturer in environmental epidemiology at the Centre for Environmental Health and Sustainability at the University of Leicester.