While many of us may find the sounds of chewing or breathing off-putting, for some they're unbearable - and new research has shown their brains are going into overdrive.
The team led from Newcastle University, report new findings of the physical basis for people suffering from a condition called misophonia, a disorder where they have a hatred of sounds such as eating, chewing or repeated pen clicking. Called "trigger sounds" by the misophonia community, the response can be an immediate and intense fight or flight feeling.
Publishing today in Current Biology, the researchers report the first evidence of clear changes in the structure of the brain's frontal lobe in sufferers of misophonia and also report changes in the brain activity.
Brain imaging revealed that people with the condition have an abnormality in the emotional control mechanism which causes their brains to go into overdrive on hearing trigger sounds.
Researchers also found brain activity originated from a different connectivity pattern to the frontal lobe. This is normally responsible for suppressing the abnormal reaction to sounds. The researchers also found that trigger sounds evoked a heightened physiological response with increased heart rate and sweating in people with misophonia.
Dr Sukhbinder Kumar from the Institute of Neuroscience at Newcastle University and the Wellcome Centre for NeuroImaging at University College London (UCL) led the research which was supported by Wellcome. He said: "For many people with misophonia, this will come as welcome news as for the first time we have demonstrated a difference in brain structure and function in sufferers.
"Patients with misophonia had strikingly similar clinical features and yet the syndrome is not recognised in any of the current clinical diagnostic schemes. This study demonstrates the critical brain changes as further evidence to convince a sceptical medical community that this is a genuine disorder."
Using brain scans carried out with Magnetic resonance imaging (MRI) the team revealed a physical difference in the frontal lobe between the cerebral hemispheres of people with misophonia - with higher myelination in the grey matter of ventromedial prefrontal cortex (vmPFC).
The study also used functional MRI to measure the brain activity of people with and without misophonia while they were listening to a range of sounds such as;
- Rain, busy café, a kettle boiling - neutral sounds
- Baby crying, a person screaming - unpleasant sounds
- The sounds of breathing, eating - trigger sounds
This showed abnormal connections between this frontal-lobe area and an area called the anterior insular cortex (AIC). This area is in the grey matter of the brain but buried in a deep fold at the side of the brain and is known to be involved in processing emotions and integrating signals both from the body and outside world.
When presented with trigger sounds activity goes up in both areas in misophonic subjects, whilst in normal subjects the activity goes up in the AIC but down in the frontal area. The team think that this reflects an abnormality of a control mechanism between the frontal lobe and AIC.
Tim Griffiths, Professor of Cognitive Neurology at Newcastle University and UCL adds: "I hope this will reassure sufferers. I was part of the sceptical community myself until we saw patients in the clinic and understood how strikingly similar the features are.
"We now have evidence to establish the basis for the disorder through the differences in brain control mechanism in misophonia. This will suggest therapeutic manipulations and encourage a search for similar mechanisms in other conditions associated with abnormal emotional reactions."
And for Dr Kumar this research opens up future possibilities for therapy: "My hope is to identify the brain signature of the trigger sounds - those signatures can be used for treatment such as for neuro-feedback for example, where people can self-regulate their reactions by looking at what kind of brain activity is being produced."
Reference: Kumar, S., Hancock, OT., Sedley,, W., Winston, JS., Callaghan, MF., Allen M., Cope, TE., Gander, PE., Bamiou, DE., Griffiths, TD (2017). The brain basis for misophonia. Current Biology (in Press) DOI: 10.1016/j.cub.2016.12.048
Case study: Olana's story
Olana Tansley-Hancock, 29, from Ashford in Kent was just 8 when family meals became unbearable for her as she explains:
"The noise of my family eating forced me to retreat to my own bedroom for meals. I can only describe it as a feeling of wanting to punch people in the face when I heard the noise of them eating - and anyone who knows me will say that doesn't sound like me.
"My family were supportive and it was only at University that I found it becoming more of an issue. I found it spread to my housemates and to other noises and it all came to a head on a train journey when I had changed carriages 7 times as the noise of people eating or rustling papers was unbearable.
"When I saw my GP at the time, he laughed at me. Then I tried a counsellor but in my case, that made it worse as it made me even more sensitive to sound.
"It was only after I searched on the internet for 'hearing people eat makes me want to punch them' that I heard of misophonia - and through the misophonia UK website got involved with the research.
"Now, I'm a lot better probably through a combination of better bodily awareness and changes I've made to my lifestyle. I mediate and have reduced my caffeine and alcohol intake and I am always prepared - so take earplugs on a journey so I can watch a film and ask for headphones at the cinema so block out the sound of people rustling and eating. These steps have helped me manage and understand my condition better.
"This research is a huge relief as it shows there is a physical basis for misophonia which should help others understand the condition. It also opens up the opportunity for better management."
The term was coined by US scientists Pawel and Margaret Jastreboff in 2001.
Onset age tends to be pre-teens.
Trigger sounds are most commonly focused on eating, breathing and hand noises (typing/pen clicking).
The reaction starts with the sound and often develops to include actions associated with the sound and even anticipation of those actions.
Responses can include irritation, upset, disgust and extreme rage.
There is no known cure. Misophonia UK recommends seeing your GP in the first instance and asking to be referred to a consultant familiar with the condition. Ideally an audiological physician or a neurologist.