Misophonia: Supersensitive brain connection explains why some people hate the sound of others eating
The common disorder has been traced to increased connectivity between the brain’s hearing and movement systems.
A new study led by researchers from Newcastle University, working at the Wellcome Centre for Human Neuroimaging, has discovered abnormal communication between areas of the brain that process sound, and those that represent movement of the face, mouth and throat.
The study, published in the Journal of Neuroscience, identifies increased brain connectivity as the cause of misophonia for the first time.
Lead author Dr Sukhbinder Kumar, a research fellow at Newcastle University and University College London said: “Our findings indicate that for people with misophonia there is abnormal communication between the auditory and motor brain regions – you could describe it as a supersensitised connection.”
Misophonia (literally, “hatred of sound”) is a common disorder in which certain sounds such as chewing or breathing trigger a distressing, involuntary emotional reaction. Common trigger sounds include chewing, speaking or breathing.
The reaction is often extreme, and tends to consist of some combination of anger, disgust, fight-or-flight response, anger towards the person making the sound, or an urge to leave the situation. The condition is common, and those with the more severe forms can find themselves unable to tolerate family, work, public or social situations.
So far, misophonia has largely been considered a disorder of sound processing. However, this new research suggests that it is not just an emotional reaction driven by the auditory part of the brain. In fact, the study found that the auditory cortex responds normally in people with misophonia.
Rather, the disorder is due to activity in the brain movement systems that usually produce these trigger sounds. People with misophonia showed increased communication between the auditory cortex and motor control areas in the face, mouth, and throat.
What’s more, these motor control regions were strongly activated in people with misophonia in response to trigger sounds only, but not to other types of sounds or in people without misophonia.
The researchers also saw a similar pattern of communication between visual and motor regions, which suggests a possible visual trigger for misophonia.
“This lead us to believe that this communication activates something called the ‘mirror system’, which helps us process movements made by other individuals by activating our own brain in a similar way – as if we were making that movement ourselves,” explains Dr Kumar.
“We think that in people with misophonia involuntary overactivation of the mirror system leads to some kind of sense that sounds made by other people are intruding into their bodies, outside of their control.”
Dr Kumar added: “Interestingly, some people with misophonia can lessen their symptoms by mimicking the action generating the trigger sound, which might indicate restoring a sense of control.”
Professor Tim Griffiths, Principal Investigator of the Centre’s Auditory Cognition team and senior author on the study, hopes that the findings could help them develop more effective treatments for misophonia in future:
“The study provides new ways to think about the treatment options for misophonia. Instead of focussing on sound centres in the brain, which many existing therapies do, effective therapies should consider motor areas of the brain as well.”