From incessant pen-clicking to relentless slurping, people with misophonia find these noises not just annoying, but enraging. Researchers are investigating the neurological mechanisms that drive this disorder to hopefully one day find a treatment for it.

Misophonia Trigger Warning: To skip past a series of sounds that may trigger listeners with misophonia (at 0:28 to 0:52):, please skip to 0:52.

Host: Stephanie DeMarco

Guests: 

M. Zachary Rosenthal at Duke University 

 

Phillip Gander at the University of Iowa

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DDN Dialogues is a new podcast from Drug Discovery News. Join us as we explore the stories behind the latest advances in drug discovery research.

Transcript

Stephanie DeMarco: Welcome to DDN Dialogues, a new podcast from Drug Discovery News. I’m your host, Stephanie DeMarco. Join me as we explore the stories behind the latest advances in drug discovery research.

Today’s story is, fittingly, all about sounds, human-created ones to be exact.

We all find certain sounds a little annoying. Like listening to that one coworker clicking a pen during a meeting or chewing on crunchy potato chips at lunch. But for some people, these noises are not just mildly irritating, they are enraging. Scientists call this hatred for certain sounds misophonia. But what causes this intense, emotional response, and can scientists find a cure?

Misophonia is not exactly a rare condition — scientists estimate that 6 to 20% of people have it. But the neurological mechanisms that cause misophonia are not well understood. That mystery drives researchers like Duke University clinical psychologist, Zach Rosenthal to investigate ways to treat it.

Zach Rosenthal:  Probably all of us are bothered by certain sounds. But not all of us have misophonia. People with misophonia are not only just bothered, but the degree to which they are bothered, looks more like having very, very strong emotional reactions — automatic, uncontrollable physiological reactions. And it really leads to significant impairment in their social functioning, or their kind of day to day, academic or occupational functioning.

DeMarco: For the most part, people with misophonia react by removing themselves from the triggering noise, whether that’s asking the person making the noise to stop or by leaving the room themselves. But Phillip Gander, a University of Iowa neuroscientist who studies misophonia, told me that sometimes the noises are so irritating that people resort to drastic measures.

Phillip Gander: I spoke with someone on a radio interview, and they were talking about how they had to leave their family essentially so that their life as they knew it was completely turned upside down. And that's thankfully not common, but it is the range of what can go on here.

DeMarco: Only in the past few years have scientists really started investigating what happens in the brains of people with misophonia when they hear a triggering sound.

One of Gander’s University of Iowa colleagues, the neuroscientist Sukhbinder Kumar, led one of the first of these studies when he was at Newcastle University. In the study, the researchers had people with and without misophonia lay in an MRI machine while playing them triggering sounds. They also played neutral sounds like falling rain and universally abrasive sounds like a baby crying or a person screaming.

Gander: What we found was only in the misophonia group did we see a large increase in brain activity, specifically to the trigger sounds — not to neutral sounds, and not to what we would all generally describe as unpleasant sounds like nails on a chalkboard or loud car crash or things like that.

DeMarco: Initially, the scientists thought that brain regions like the auditory cortex, which processes sound, or the amygdala, which regulates emotions, would activate in misophonia patients. But, they saw this spike in brain activity in an unexpected region — the anterior insula. This is a structure deep within the brain that helps process emotions, including disgust. But it also plays a role in a phenomenon called interoception. Basically, interoception is how we sense ourselves. It’s those random thoughts that pop into our heads like, “I’m hungry” or “Do I need a nap right now?” 

Gander: What's going on inside of us can greatly govern how we respond to the external world. Our sensing of our breathing or our heart rate might actually change the way that we see and hear things.

DeMarco: Kumar and his colleagues, including Gander, decided to look a little closer at the anterior insula and the brain regions it connects to. To do this, they had people with and without misophonia lay in that MRI scanner again and simply do nothing at all.

Gander: Whatever is different about their brains is being expressed even at rest. And lo and behold, when he looked across the whole brain and tried to find what was different between the control group that didn't have misophonia and the misophonia group, he found an area in motor cortex, specifically the ventral premotor cortex and this also happens to be a motor area involved with oral-facial movements and perception. Oh okay, well that makes a little bit of sense maybe, right?

DeMarco: Right. But if people with misophonia get triggered by other people’s orofacial noises, why would their own brain regions involved in orofacial movements light up?

Gander: This invited a previously taboo research area in the neurosciences called mirror neurons.

DeMarco: Mirror neurons are a special type of neuron that activate both when people see someone perform an action and when people do the action themselves. 

Scientists discovered mirror neurons completely by accident. In 1992, a group of researchers at the University of Parma had hooked up electrodes to single neurons in a few monkeys’ brains. They wanted to study the activity of these neurons while the monkeys performed a particular action like grasping a piece of food or placing food inside a box. At first, everything went as expected. The monkey picked up a piece of food. A neuron fired.

But as the researchers started to reset the experimental setup, one of them picked up a piece of food across from a monkey. 

DeMarco: The same neuron that fired when the monkey picked up the food fired again, but the monkey hadn’t moved a muscle. It had only watched the scientist do the action.

Gander: The whole neuroscience world, after they publish this, is like, “Oh my goodness! This is really really important. Maybe it emerged in primates specifically for motor learning. This whole system is then instantly tied up with the social being. This might be an interesting brain mechanism to understand better, and it might relate to what's going on here in misophonia. You're very much triggered by the actions of some other person.

DeMarco: Additional research on mirror neurons over the past few years revealed that activating a person’s mirror neurons can actually trigger emotional responses and spontaneous mimicry of the action they’re observing.

Gander: So, they don't feel like they have control over their own body, copying this action that they're observing. That would be lightly frustrating. Wouldn't it? If you felt like you were having to mimic something even though you didn't want to.

DeMarco: For now, Gander’s working theory is that the auditory and visual systems in the brain are simply receiving the triggering information. Then the anterior insula compares this information from the outside world to a person’s inner world. From there, it’s possible that mirror neurons fire and may cause a person to mimic the triggering action they’ve seen, potentially leading to feelings of frustration and anger. 

DeMarco: Gander, Kumar, and their teams are now planning to record from mirror neurons directly to test whether they play a role in misophonia.

Gander: Things are aligning kind of nicely, and we are excited about it. So, what does this mean then for treatments, right?

DeMarco: It turns out that Rosenthal and his team have already started testing psychological-based therapies for misophonia in early clinical trials.

Rosenthal: We're saying, okay, what do we know about misophonia that's probably got some shared features with other kinds of conditions like anxiety disorders, like mood disorders, as examples, and what we're doing is we're saying, okay, so what are these kinds of underlying processes that may be similar in misophonia with these other kinds of conditions? And what are the interventions that we already have that we already know can help for those processes?

So we're using a kind of pragmatic approach to help people now using cognitive behavioral therapies that are likely to help in a trans diagnostic way. And we're tailoring them to people in a really flexible way with misophonia.

DeMarco:  For people with misophonia who are not in the clinical trials, Rosenthal recommends finding ways to block out triggering sounds. Noise canceling headphones can help. People can also try avoiding situations where they know they will hear highly triggering noises. 

Rosenthal: We would want to encourage people to try not to avoid all triggering situations, and instead, really try to minimize that as much as is feasible so that they can start to try to learn as best as possible how to adjust and cope more effectively. That is easier said than done. That is very hard to do, but it is part of what people with misophonia do to manage their difficulties.

Another thing they can do is they can stay educated. So, the science of misophonia is rapidly advancing. And one thing that can be done is to really try to keep aware of what's going on with the science. And that matters because if you understand what's going on with you and your body, then you can predict it better, and you can start to feel a little bit more in control of what's going on.

DeMarco: Neuroscientists like Gander, Rosenthal, and their colleagues will continue to investigate the neural connections that drive misophonia, and hopefully one day soon that research will lead to new and better treatments for this condition.

That’s it for this episode of DDN Dialogues. Thank you so much for listening. Until next time, I’m your host Stephanie DeMarco. This episode of DDN Dialogues was reported, written and edited by me, with additional audio editing by Jessica Smart. To never miss an episode, subscribe to DDN Dialogues wherever you get your podcasts.

And remember, the next time you’re about to take a bite out of a particularly crunchy food, know that you may activate someone’s anterior insula, and they may not be too happy about it.