The History of Misophonia Research, by Jennifer Jo-Brout, Psy.D (Part II of III)

The small body of research emerging in misophonia tends to address 4 core issues:

  1. Specific symptoms
  2. Possible causes
  3. Overlaps with other disorders
  4. The extent to which the disorder impairs suffers’ lives.

However, since misophonia is new (in the sense it was only officially recongised in 2001) the research is still in its infancy.

Classifications of disorders are usually based upon their underlying causes. Thus, if a disorder is caused by a neurological problem, we would say it is a “neurological” disorder.

However, in modern times it has become increasingly difficult to categorize disorders in this way because disorders overlap, and causality is often unknown. This, of course, adds to the confusion.

Having said that, misophonia has mostly garnered attention from researchers in the following fields:

Audiology/Otology, Psychology/Psychiatry (mainly pertaining to obsessive compulsive and related disorders)

and…

Neuroscience (mostly related to synesthesia).

I’ll go through each of these in turn:

Audiology/Otology

Research in this area is mainly confined to the Jastreboffs’ work.

However, it is very important to understand their theory, as it is both the catalyst for interest in Misophonia and has been subject to a great deal of misinterpretation.

The Jastreboffs defined Misophonia while treating patients with tinnitus[1] (ringing in the ears) and hyperacusis (severe intolerance for loud sounds).

The Jastreboff’s made a very important distinction, specifically between Hyperacusis and Misophonia.  Hyperacusis patients aversely react to loud noises whereas misophonics react to “repetitive or pattern based noises” regardless of decibel level (Jastreboff & Jastreboff, 2014).

This is the first important distinction:

Misophonia – aversive response to repetitive and patterned based sounds that may often be quiet, or “soft”

Hyperacusis – aversive response to loud sounds

According to the Jastreboff’s both conditions are subsumed under “Decreased Sound Tolerance” and both conditions relate to “aberrant” or “atypical” associations between the auditory and the limbic system.

Note, the limbic system is known to be the “emotional center” of the brain.

However, regarding Hyperacusis, the Jastreboff’s hypothesized that the brain circuitry involved was purely subconscious.

In other words, the brain regions and connections amongst these brain structures/regions were completely out of control of the “conscious” or “thinking part” of our brain.

To simplify, in hyperacusis one part of the brain is telling the other to perceive sounds much more loudly than they really are, and this is going on without any involvement of the part of the brain that is involved in conscious thought (where more sophisticated kinds of memory and organization that only human beings are capable of occurs).

The next important distinction:

Misophonia: Abnormal connections amongst auditory, emotional and “thinking” part of brain

Hyperacusis – Abnormal connection in auditory and emotional part of the brain (not “thinking part”).

In addition, unlike hyperacusis patients who responded to loud noises all the time, misophonics seem varied in their responses. That is, the patients the Jastreboffs treated reported a variety of emotions in response to sounds, ranging from annoyance to rage, and including fear and avoidance of situations/places in which trigger sounds might be present, and numerous other mixed descriptors.

The Jastreboff’s also noted that their patients reacted to some people and not others (and in some places but not others).

This led them to believe that misophonic individuals had made negative associations between specific noises and specific people, or between specific noises and particular experiences and/or places.

This meant that these responses were “learned”. This is where the more conscious part of the brain (or the “thinking brain”) becomes relevant.

Simplified, the Jastreboff’s view, sounds (processed in the “auditory part of the brain”) were associated during a negative experience with a person, place or experience within the limbic system (the “emotional part of the brain) and then stored in memory (via the “thinking part of the brain”).

Once this negative association is formed, every time the same sound is encountered, a person with misophonia will experience what’s known as autonomic arousal.

Autonomic arousal refers to physiological arousal associated with what is commonly referred to as the “fight or flight” syndrome (although it can be experienced at lower levels without fight/flight occurring).

The Jastreboffs’ did not venture to study Misophonia “in a lab” in order to support their theory, but instead began treating patients under the assumption that although Misophonia is a neurologically based disorder, the negative associations that have been made between the sounds and the particular experiences could be re-trained through making new and positive associations with sounds.

Psychiatry/Psychology & Neuroscience

In psychology/psychiatry, commonalities between obsessive compulsive and related disorders and, to a lesser extent, generalized anxiety have been investigated.

In neuroscience, models of misophonia as a form of synesthesia are proposed. Across this research is also discussion of “general sensory sensitivities,” “sensory-defensiveness” and “multisensory processing” (e.g. Wu, Lewin, Murphy, & Storch, 2014).

Obsessive Compulsive (OCD) and Related Disorders

In psychology, Obsessive Compulsive and Related Disorders have received attention in this small but growing body of literature on misophonia.

Schröder, Vulink, and Denys (2013) recruited 42 patients who self-reported misophonia symptoms. They were interviewed by a psychiatrist and given various measures pertaining to neuropsychiatric diagnosis.

Notably, the authors found the highest incidence of overlap with the DSM-IV TR Obsessive Compulsive Personality Disorders.

Schröder, et al. (2013) proposed that Misophonia should be considered a discrete disorder under the broader classification Obsessive and Compulsive Related Disorders in the DSM-5.

The researchers recruited from a mental health clinic, and as Jastreboff & Jastreboff (2014) state, this may have biased their sample.

In addition, it is too early in the stage of research to label misophonia as a psychiatric disorder. Notably, the authors recognized a symptom overlap with Sensory Processing Disorder (SPD), but a misunderstanding of Sensory Processing Disorder may have impacted their quantitative analysis.

Specifically, in their description of SPD they state that individuals with SPD only react to “loud” sounds and not to the repetitive sounds (the sounds indicated in Misophonia).

This is not true.

The research in SPD does not differentiate between loud or patterned noises, and on many of the Sensory Processing Scales are items that include both loud noises and repetitive noises. Therefore, the overlap with Sensory Processing Disorders should not be disregarded.

Wu, Lewin, Murphy, and Storch (2014) investigated the incidence, phenomenology, correlates, and level of impairment associated with misophonia symptoms in 483 undergraduate students through self-report measures. In their sample, nearly 20% of participants reported clinically significant misophonic symptoms.

These symptoms were strongly associated with measures of general life impairment and sensory sensitivities, as well as moderate associations with obsessive-compulsive, anxiety, and depressive symptoms.

The authors report that the symptom association with sensory sensitivities may indicate that selective sound sensitivities may be linked to higher occurrences of other types of sensory defensiveness as well (Baguley & McFerran, 2011; Stansfeld, Clark, Jenkins & Tarnopolsky, 1985).

Recognizing other types of sensory sensitivities in individuals, such as tactile sensitivity, may help in the detection of concurrent increased sound sensitivities. In addition, the authors report that anxiety mediated the relationship between misophonia and anger outbursts. [2]

Finally, as limitations to their study, the authors note that most study participants were female and that only self-report measures were used.

However, in a case study of two children, the researchers report that Misophonia appears to be a psychiatric disorder that is highly correlated with OCD.

In addition, due to accommodations parents have made so that children may avoid “trigger sounds” at home, trigger sounds may have in fact worsened. That is, lack of exposure to these particular noises have worsened the severity of the response. In general, the OCD researcher/clinicians agree that patients would benefit from by re-conditioning therapy similar to that of the Jastreboff’s.

However, OCD clinicians propose using a behavior-based therapy more similar to “exposure therapy” in which patients would be gently exposed to the sounds they find aversive until they habituate (or become used to them). Notably, there are only approximately 5 papers as of yet, and sample sizes are small.

Synesthesia Research

Edelstein, Brang, Rouw, and Ramachandran (2013) found some similarities between Synesthesia and Misophonia. Edelstein et al. proposed that misophonia “displays similarities” to synesthesia.  Edelstein et al. used both self-report (qualitative interviews) and physiologic measures (Skin Conductance Response, or SCR) to characterize aversive reactivity in Misophonia:

“In synesthesia, as in misophonia, particular sensory stimuli evoke particular and consistent, additional sensations and associations…In short, a pathological distortion of connections between the auditory cortex and limbic structures could cause a form of sound-emotion synesthesia” (Edelstein et al., 2013).

The authors note that limitations of the study include small sample size, a lack of screening for psychiatric or psychological problems (no measures of mental health disorders were included), and that SCR measures autonomic arousal, but does not describe the nature of the emotion associated with that autonomic arousal.

As you may have noted, the synesthesia research is applicable to Misophonia as it directly addresses the aberrant brain connectivity that the Jastreboff’s originally conceived of.

While synesthesia research does not directly translate into treatment, it can certainly further our understanding of the disorder and therefore inform treatment. There are a few more synesthesia research studies underway and it will be interesting to find out results.

Please Note: This is a summary review, and a complete references for Misophonia Journal Articles in the psychology/psychiatry category are provided upon request.

So what does all this mean and how can we tie this research together?

Read Part III Here

[1] Tinnitus (ringing in the ears) is a common problem, affecting about 17% of the general population (Jastreboff, P.J., & Gray, W.C.,; Gold, S.L 1996)
[2] Notably, studies that include the relationship of SOR and anxiety (e.g. Ben-Sasson, 2009, 2010; Carter, & Briggs Gowan, 2009; LaneReynolds, & Dumenci, 2012; LaneReynolds, & Thacker, 2010) may inform how anxiety mediates misophonia in general and in regard to anger outbursts