Misophonia: Why Some People Get Easily Angered by Eating or Breathing Sounds
A new study led by the Newcastle University revealed that people suffering from the condition "misophonia" have changes in the structure of the brain's frontal lobe and brain activity.
The study, published in the journal Current Biology, showed for the first time physical basis why people who have misophonia can't handle specific trigger sounds, such as chewing and breathing.
"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," said lead investigator Dr. Sukhbinder Kumar from the Institute of Neuroscience at Newcastle University and the Wellcome Centre for NeuroImaging at University College London (UCL), in a press release. "This study demonstrates the critical brain changes as further evidence to convince a sceptical medical community that this is a genuine disorder."
For the study, the researchers used magnetic resonance imaging (MRI) to scan the brains of 20 people suffering from misophonia. The brain scans showed that people with misophonia have higher myelination in the grey matter of ventromedial prefrontal cortex (vmPFC). This abnormality in the emotional control mechanism of the brain is responsible for making the brain of people with misophonia to overdrive.
The researchers also conducted functional MRI scans to 22 healthy people, in addition to 20 who have misophonia, while they were listening to a range of sounds. The sounds were divided into three categories: neutral, unpleasant and trigger sounds. Neutral sounds include rain, busy café, a kettle burning. On the other hand, unpleasant sounds include baby crying and a person screaming. Trigger sounds include breathing and eating.
Patients with misophonia showed abnormal connection between the frontal lobe and an area known as anterior insular cortex (AIC). AIC is involved in processing emotions and integrating signals both from the body and the outside world. The researchers noticed that activity in both the AIC and the frontal lobe goes up when a patient with misophonia hear trigger sounds. Meanwhile, healthy patients hearing trigger sounds have increased activity in the AIC but decreased activity in the frontal area.
Aside from the difference in brain structure and activity, the researchers also noted that trigger sounds may evoke heightened physiological response with increased heart rate and sweating in people with misophonia.