Misophonia, also known as selective sound sensitivity syndrome, is a condition characterized by an extreme emotional response and aversion to certain sounds. Individuals with misophonia experience a fight-or-flight reaction to everyday sounds like chewing, tapping, breathing noises, and more. This article will explore the potential causes of misophonia and provide an overview of the latest research on this complex condition.
What is misophonia?
Misophonia is a neurological disorder in which certain sounds trigger emotional or physiological responses within an individual. The term literally means “hatred of sound” in Greek. For people with misophonia, also called misophonics, exposure to trigger sounds leads to feelings of anxiety, anger, or disgust. The reaction can be instantaneous and range from mild irritation to full “fight-or-flight” mode.
Common trigger sounds include:
- Chewing or crunching food
- Repetitive tapping
- Sniffling or throat-clearing
- Typing on a keyboard
- Ticking clocks
- Rustling papers
Misophonics are not bothered by these sounds universally. Rather, they associate specific trigger sounds with specific people, often family members or coworkers. For example, the sound of a spouse chewing may be infuriating while hearing a stranger chew does not provoke a reaction.
Prevalence of misophonia
There are no definitive statistics regarding the prevalence of misophonia. However, studies suggest it affects approximately 10-20% of the population to some degree. Some experts believe misophonia is underdiagnosed and the actual rates may be higher.
Misophonia typically develops in late childhood or early adolescence, usually appearing around ages 9-13. Females are diagnosed more frequently than males, at nearly a 3:1 ratio.
Misophonia appears to have a genetic component. People with misophonia are twice as likely to have a first-degree relative with the condition compared to the general population.
Characteristics of misophonia
In addition to negative emotional responses, individuals with misophonia may develop physical symptoms when exposed to trigger noises. These can include:
- Increased heart rate or blood pressure
- Sweating
- Tightness in the chest
- Nausea
- Dizziness
People with misophonia typically attempt to avoid the unpleasant symptoms by:
- Avoiding situations where they will hear trigger noises
- Wearing headphones or earplugs
- Mimicking sounds to drown out triggers
- Having others make trigger noises on their behalf
If they cannot escape the noise, misophonics may have outbursts of anger or anxiety. In rare cases, this leads to violent behavior.
Misophonia vs. hyperacusis
Misophonia has some overlap with a condition called hyperacusis. However, these two sound sensitivities have distinct differences:
| Misophonia | Hyperacusis |
|---|---|
| Triggered by specific sounds, usually made by humans | Sensitivity to a broad range of sounds at certain volumes |
| Primary reaction is anger or disgust | Primary reaction is fear or pain |
| Not necessarily related to volume | Triggered by loud noises |
An individual can have misophonia, hyperacusis, both conditions, or neither.
Potential causes of misophonia
The underlying mechanisms of misophonia are not yet fully understood. Research is ongoing to determine the root cause. Here are some of the leading theories:
Abnormal auditory processing
Several studies indicate those with misophonia have atypical auditory processing. This means there are differences in how their brains respond to sounds on a neurological level.
In misophonics, certain sounds appear to activate the autonomic nervous system, which controls functions like heart rate and breathing. The limbic system, responsible for emotions and behavior, is also highly stimulated.
Brain imaging scans show hyperconnectivity between auditory regions and emotional processing regions in people with misophonia. When they hear trigger noises, larger couplings occur between the cortex and limbic system.
Additionally, misophonics show weakened connectivity between auditory and reward regions. This may explain why pleasant sounds are not able to override their sensitivity.
Faulty emotional control
Another working theory is that misophonia results from problems with emotional regulation. Those with misophonia appear to have excessive limbic reactivity along with lower cognitive control.
The anterior insular cortex (AIC) is the part of the brain tied to detecting stimuli in the environment, emotions, and thought processes. Studies indicate misophonics have overactive AICs which makes them highly sensitive to external sounds.
Meanwhile, the prefrontal cortex which manages emotions seems to be underactive in those with misophonia. This contributes to outsized emotional reactions to triggers.
Abnormal conditioned responses
Misophonia also resembles a conditioned reflex disorder called synesthesia. This is when cues that normally only stimulate one sense involuntarily activate additional senses.
Similarly, misophonics develop intense connections between certain sounds and negative emotions/memories. Hearing the sound automatically elicits a conditioned, involuntary response.
Research indicates misophonia trigger associations form through a Pavlovian process. Originally neutral sounds become tied to concurrent negative situations and provoke a reaction even without the context.
As evidence, people with misophonia report the first trigger sounds that bothered them were usually related to family members or significant events.
Dysfunctional mirror neurons
Mirror neurons are cells that cause parts of your brain to activate when you perform an action or observe someone else performing the same action. They play a key role in social interactions.
According to one hypothesis, people with misophonia have oversensitive mirror neuron systems. Watching someone make a trigger motion, like chewing, excessively activates parts of their brain involved in movement.
As a result, observing a trigger action subconsciously makes the misophonic individual feel like they are chewing themselves. This creates discomfort and makes the sound unpleasant.
Abnormal serotonin levels
Serotonin is a neurotransmitter involved in regulating learning, memory, mood, sleep, and more. Some data indicates misophonics have lower than normal serotonin levels.
One small study found 70% of participants with misophonia had serotonin deficiencies. Increasing serotonin reduced symptoms for some people.
Low serotonin is associated with increased reactivity to stressors. This aligns with the amplified reactions misophonics have to sounds based on their serotonin levels.
Theories requiring more research
There are additional theories about the origins of misophonia that require further scientific investigation:
- Hypervigilance – Misophonics may subconsciously focus too much on sounds in their environment.
- Tinnitus – Misophonia could stem from a patient’s attempts to mask or avoid the phantom sounds of tinnitus.
- Obsessive-compulsive disorder – OCD symptoms seem to occur more often in misophonics.
- Neurodevelopment factors – Issues in the development of neural pathways may play a role.
- Genetics – Specific genes could make someone predisposed to misophonia.
Overall, experts agree misophonia likely stems from a complex combination of elements rather than a single cause. More multidisciplinary research is required to unravel all the involved factors.
Recent research on misophonia causes
Here are some notable recent studies providing insight on possible misophonia causes:
- A 2021 study found misophonics have enhanced theta wave synchrony between auditory and medial frontal cortex regions when exposed to sounds. This demonstrates abnormal neurological responses.
- An analysis in 2020 showed misophonics have higher grey matter volume in several regions involved with emotion processing and memory formation.
- A 2019 EEG study revealed those with misophonia have greater viscerosomatic resonance with sounds. This is when internal bodily sensations get paired with external audio cues.
- Research in 2017 indicated the anterior insula cortex shows atypical activity in misophonics hearing trigger sounds. The insula processes emotions so this points to faulty affective processing.
Treatment and management of misophonia
Unfortunately there is no cure for misophonia yet. However, a range of strategies can help patients manage their symptoms:
- Cognitive behavioral therapy (CBT) – CBT helps patients change their thought patterns about sounds.
- Exposure therapy – Gradually exposing patients to increasing levels of trigger sounds can desensitize them.
- Relaxation techniques – Methods like meditation help patients calmly cope with triggers.
- Trigger avoidance – Preventing encounters with sounds through measures like wearing earplugs.
- Medications – Drugs like SSRIs help control related symptoms for some patients.
- Misophonia therapy apps – Apps with sound-modification features can help make triggers more tolerable.
- Tinnitus retraining therapy – TRT uses sound therapy to help neurologically retrain auditory pathways.
With proper management, many misophonia patients see an improvement in their quality of life. Support groups can also help patients realize they are not alone in this condition.
Coping strategies for misophonia families
For family members of someone with misophonia, empathy and preventative measures go a long way in maintaining a peaceful home environment. Some tips include:
- Learning what sounds trigger the misophonic person and avoiding them when possible
- Establishing rules like no eating in the same room together
- Providing separate quiet spaces the person can retreat to
- Agreeing to signal each other discreetly to stop a sound
- Wearing headphones to listen to music or white noise while eating
- Seeking family counseling to constructively discuss the condition
With understanding and accommodation, families can find balanced ways to interact that account for misophonia. Professional help from psychologists may also facilitate healthier coping mechanisms.
Conclusion
Misophonia is a complex neurological and emotional disorder triggered by specific sounds unique to each patient. While research is still unraveling the precise causes, it likely stems from some combination of abnormal auditory processing, poor emotional control, genetic factors, and conditioned neural pathways.
To manage misophonia, a multidisciplinary treatment approach can help patients control their extreme reactions through therapies, sound modifications, medication, and other strategies. With continued research, more effective treatments will hopefully emerge to address the causes of this challenging condition at their core.
