The neurophysiological approach to misophonia: Theory and treatment

Dissociable effects of hyperacusis and misophonia severity imply different mechanisms of decreased sound tolerance

OBJECTIVE

It is thought that decreased sound tolerance can be subdivided into distinct types including misophonia (involving specific trigger sounds) and hyperacusis (broader in profile). However, there are few established methods for differentially assessing these disorders and this is complicated by the fact that some measures (e.g. the HQ Hyperacusis Questionnaire) were developed before the concept of misophonia was accepted.

DESIGN/STUDY SAMPLE

We took a group of N = 119 participants with misophonia (varying in severity) and asked them about the presence of hyperacusis (based on a scoping review definition).

RESULTS

Scores for some items on the HQ were correlated with scores for misophonia severity (e.g. social impact of sound) and others with scores for hyperacusis (e.g. ability to concentrate in noise). Similarly, some trigger sounds were more indicative of hyperacusis (e.g. dishes being stacked) and others were more indicative of misophonia in the absence of hyperacusis (e.g. chewing).

CONCLUSIONS

These double dissociations provide compelling evidence for separable forms of sound intolerance. Moreover, our research suggests that a single-item question about hyperacusis is associated with other characteristics of hyperacusis, even when assessed 18 months later.

A Retrospective Study Distinguishing between Hyperacusis and Misophonia in children with Auditory Processing Disorder (APD)

OBJECTIVES

Decreased sound tolerance (DST) is common in children with auditory processing disorder (APD). This study aimed to differentiate between hyperacusis and misophonia in children with APD.

DESIGN

A retrospective study evaluating outcomes of structured history and co-morbidity following Research Domain Criteria (RDoC) frame-work. Misophonia was considered as oversensitivity to eating/chewing sounds and hyperacusis as oversensitivity to other sounds.

STUDY SAMPLE

Two hundred and seventy-nine children (160 males; 119 females), 6-16 year-olds with NVIQ ≥80, diagnosed with APD between January 2021 and December 2022.

RESULTS

One hundred and forty-three out of 279 children with APD had DST, of which 107 had hyperacusis (without misophonia) and 36 had misophonia. Misophonia co-existed with hyperacusis in 35 children (97 %), and in one child misophonia occurred without hyperacusis. Misophonia was prevalent in older children, in females, and those with tinnitus. Fear and being upset were predominant emotional responses in hyperacusis (without misophonia) while disgust and verbal abuse were prevalent in misophonia (with or without hyperacusis). Compared to children without DST, the hyperacusis (without misophonia) and misophonia (with or without hyperacusis) groups had significant higher prevalence of ADHD, anxiety, and language impairment. Educational difficulties were similar in APD irrespective of the presence or absence of DST. Despite higher tinnitus prevalence in misophonia (with or without hyperacusis) along with similar co-morbidities and educational difficulties in both hyperacusis (without misophonia) and misophonia (with or without hyperacusis), the misophonia (with or without hyperacusis) group surprisingly had less support at school which was reflected in fewer Education, Health and Care Plan (EHCP).

CONCLUSIONS

In APD misophonia mostly co-exists with hyperacusis, with differences in emotional responses, tinnitus prevalence, and gender distribution when compared to hyperacusis (without misophonia). Increase in awareness about misophonia is needed, as children with misophonia may have unidentified needs. Larger scale prospective study is required to clarify if misophonia evolves from hyperacusis, and to explore the factors underlying 'misophonia with hyperacusis' and 'misophonia without hyperacusis'. For clarity, DST studies need to specify if hyperacusis or misophonia co-existed when referring to hyperacusis or misophonia.

A social cognition perspective on misophonia

Misophonia is commonly classified by intense emotional reactions to common everyday sounds. The condition has an impact both on the mental health of its sufferers and societally. As yet, formal models on the basis of misophonia are in their infancy. Based on developing behavioural and neuroscientific research we are gaining a growing understanding of the phenomenology and empirical findings in misophonia, such as the importance of context, types of coping strategies used and the activation of particular brain regions. In this article, we argue for a model of misophonia that includes not only the sound but also the context within which sound is perceived and the emotional reaction triggered. We review the current behavioural and neuroimaging literature, which lends support to this idea. Based on the current evidence, we propose that misophonia should be understood within the broader context of social perception and cognition, and not restricted within the narrow domain of being a disorder of auditory processing. We discuss the evidence in support of this hypothesis, as well as the implications for potential treatment approaches. This article is part of the theme issue 'Sensing and feeling: an integrative approach to sensory processing and emotional experience'.

Normal linear and non-linear cochlear mechanisms and efferent system functioning in individuals with misophonia

BACKGROUND

Misophonia, a condition characterized by heightened sensitivity and strong emotional reactions to specific sounds, has sparked considerable interest and debate regarding its underlying auditory mechanisms. The study aimed to understand the auditory underpinnings of two such potential inner ear systems, non-linear and linear outer hair cell functioning along with auditory efferent functioning in individuals with misophonia.

METHODS

40 ears with misophonia (20 participants) and 37 ears without misophonia (20 participants), both having normal hearing sensitivity were included in this study. Transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) were obtained in two conditions (with and without contralateral noise).

RESULTS

Results of independent-samples t-test showed no statistically significant difference (p > 0.05) in the absolute amplitudes of both TEOAEs and DPOAEs between the individuals with and without misophonia. There was no statistically significant difference (p > 0.05) observed in the magnitude of suppression amplitude between the two groups for in both TEOAEs and DPOAEs between individuals with and without misophonia.

CONCLUSION

These results suggest that the cochlear and efferent auditory underpinnings examined in this study may not be major contributors to the development or manifestation of misophonia.

Did Kant suffer from misophonia?

Misophonia is a disorder of decreased tolerance to specific sounds, often produced by humans but not always, which can trigger intense emotional reactions (anger, disgust etc.). This relatively prevalent disorder can cause a reduction in the quality of life. The causes of misophonia are still unclear. In this article, we develop a hypothesis suggesting that misophonia can be caused by a failure in the organization of the perceived world. The perceived world is the result of both the structure of human thought and the many conditioning factors that punctuate human life, particularly social conditioning. It is made up of abstract symbols that map the world and help humans to orient himself in a potentially dangerous environment. In this context, the role of social rules acquired throughout life is considerable. Table manners, for example, are a set of deeply regulated and controlled behaviors (it's considered impolite to eat with the mouth open and to make noise while eating), which contribute to shape the way the perceived world is organized. So it's not surprising to find sounds from the mouth (chewing etc.) among the most common misophonic sound triggers. Politeness can be seen as an act of obedience to moral rules or courtesy, which is a prerequisite for peaceful social relations. Beyond this example, we also argue that any sound can become a misophonic trigger as long as it is not integrated into the perceived ordered and harmonious world, because it is considered an "anomaly," i.e., a disorder, an immorality or a vulgarity.

Differential cortical activation patterns: pioneering sub-classification of tinnitus with and without hyperacusis by combining audiometry, gamma oscillations, and hemodynamics

The ongoing controversies about the neural basis of tinnitus, whether linked with central neural gain or not, may hamper efforts to develop therapies. We asked to what extent measurable audiometric characteristics of tinnitus without (T) or with co-occurrence of hyperacusis (TH) are distinguishable on the level of cortical responses. To accomplish this, electroencephalography (EEG) and concurrent functional near-infrared spectroscopy (fNIRS) were measured while patients performed an attentionally demanding auditory discrimination task using stimuli within the individual tinnitus frequency (fTin) and a reference frequency (fRef). Resting-state-fMRI-based functional connectivity (rs-fMRI-bfc) in ascending auditory nuclei (AAN), the primary auditory cortex (AC-I), and four other regions relevant for directing attention or regulating distress in temporal, parietal, and prefrontal cortex was compiled and compared to EEG and concurrent fNIRS activity in the same brain areas. We observed no group differences in pure-tone audiometry (PTA) between 10 and 16 kHz. However, the PTA threshold around the tinnitus pitch was positively correlated with the self-rated tinnitus loudness and also correlated with distress in T-groups, while TH experienced their tinnitus loudness at minimal loudness levels already with maximal suffering scores. The T-group exhibited prolonged auditory brain stem (ABR) wave I latency and reduced ABR wave V amplitudes (indicating reduced neural synchrony in the brainstem), which were associated with lower rs-fMRI-bfc between AAN and the AC-I, as observed in previous studies. In T-subjects, these features were linked with elevated spontaneous and reduced evoked gamma oscillations and with reduced deoxygenated hemoglobin (deoxy-Hb) concentrations in response to stimulation with lower frequencies in temporal cortex (Brodmann area (BA) 41, 42, 22), implying less synchronous auditory responses during active auditory discrimination of reference frequencies. In contrast, in the TH-group gamma oscillations and hemodynamic responses in temporoparietal regions were reversed during active discrimination of tinnitus frequencies. Our findings suggest that T and TH differ in auditory discrimination and memory-dependent directed attention during active discrimination at either tinnitus or reference frequencies, offering a test paradigm that may allow for more precise sub-classification of tinnitus and future improved treatment approaches.