Study of the Week: Scientists Discover the Cause of Misophonia

Welcome to Study of the Week from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.

If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.

 

This week’s study is…

The motor basis for misophonia

We previously published about this research in a story titled “Research Reveals the Cause Behind Misophonia” which can be found here. The study was originally published in the science research journal Journal of Neuroscience. You can view the full text of this study here.

The research team was affiliated with Newcastle University.

What Happened?

Misophonia is a unique and poorly understood condition that leads to strongly negative emotional states for patients when they hear certain sounds, particularly sounds made by other people. While this may seem like a minor condition, it can reach a level of severity that can cause serious problems for patients and their loved ones. The origin of the condition is not well understood, and the research team in this study sought to find out what could possibly be causing it by learning more about its mechanism of action.

In many cases, trigger sounds are often the result of the orofacial movements of other people; chewing is probably the most common trigger sound. The scientists hypothesized that the mirror neuron system could play a role in the condition’s origin. These neurons are triggered in the brain both when the person performs a certain action and when another person is observed performing a certain action. The researchers conducted two tests using a group of misophonia patients and a group of volunteer controls: a resting fMRI comparison and a sound-evoked fMRI comparison.

In the resting fMRI portion, 20 controls and 17 misophonia patients were involved. For the sound evoked portion, 20 patients and 22 controls were recruited. The sound evoked fMRI test included recordings of trigger sounds, generally unpleasant sounds (ex. a baby’s cry), and neutral sounds. The findings revealed that there were no differences in auditory cortex reactions to triggering noises. However, the resting fMRI study revealed that patients had a stronger link between the visual and auditory cortexes and ventral pre-motor cortex, which is linked to orofacial movement.

When trigger sounds were heard, patients also had a stronger connection between the orofacial area and the auditory cortex. The orofacial motor area was also more strongly activated when the patients were exposed to triggering noises. The scientists conclude that the brains of misophonia patients appear to be ‘hyper-mirroring’ the orofacial activity of the people around them, with sound specifically being the sensory input in which this occurs. This extra brain activity leads to the negative emotional reaction experienced by patients.

Dr. Sukhbinder Kumar, a neurologist who led this study, says:

“What we are suggesting is that in misophonia the trigger sound activates the motor area even though the person is only listening to the sound. It makes them feel like the sounds are intruding into them.”

About Misophonia

Misophonia was first proposed as medical condition in the year 2000 and is characterized by specific sounds triggering profound negative thoughts, emotions, and even physical reactions from patients. Very little is known about the condition, which is not officially classified as an auditory or psychiatric condition, and it has no clearly defined diagnostic parameters. Only minimal research has been conducted on either treatment or its prevalence. The cause and mechanism of misophonia also remains a mystery, though it may involve dysfunction of the central auditory system. Most “trigger sounds” are usually fairly soft in volume, and around 80 percent of them involve the mouth (ex. whispering, popping gum, chewing, sipping, slurping). 60 percent were repetitive sounds. To learn more about misophonia, click here.

Why Does it Matter?

In the world of medicine, the discovery of the cause of a condition is often a key touchstone in learning how to treat or cure it effectively. As of 2021, there are no evidence-based therapies available for misophonia; to escape the symptoms, most patients are simply forced to put themselves outside of situations where their known trigger sounds could occur.

It is possible to train the motor neuron system, so misophonia patients might be able to “break” the link between the trigger sound and their reaction. Some have learned that mimicking their trigger sound can help alleviate the negative reaction and calm them down. The research finding also indicates that the condition is not merely a problem with the auditory cortex, and a future therapy will have to take into consideration the areas related to movement as well.

While there is still much to learn about this poorly understood condition, the findings from this study can help lead to a better future for people living with misophonia.

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