Misophonia

Misophonia, literally "hatred of sound",^[1] is a rarely diagnosed disorder, commonly thought to be of neurological origin, in which negative emotions (anger, fright, hatred, disgust) are triggered by specific sounds. The sounds can be loud or soft.^[2] The term was coined by neuroscientist Pawel Jastreboff and biological scientist Margaret Jastreboff^[3] and is sometimes referred to as selective sound sensitivity syndrome.^[4]

Misophonia is not classified as a discrete disorder in DSM-5 or ICD-10; in 2013, three psychiatrists at the Academic Medical Center in Amsterdam formulated diagnostic criteria for it and suggested that it be classified as a separate psychiatric disorder.^[5]

A 2013 review of neurological studies and fMRI studies of the brain as it relates to the disorder^[6] postulated that abnormal or dysfunctional assessment of neural signals occurs in the anterior cingulate cortex and insular cortex. These cortices are also implicated in Tourette syndrome, and are the hub for processing anger, pain, and sensory information. Other researchers concur that the dysfunction is in central nervous system structures.^[7] It has been speculated that the anatomical location may be more central than that involved in hyperacusis.^[8]

It has been proposed that misophonia develops through classical conditioning rather than brain dysfunction^[5][9][10] although there is no clinical evidence to support this idea. Some misophonic individuals responded favorably to treatment protocols that included active extinction or counterconditioning, which are both conditioning processes that allow a conditioned reflex to decay.^{[9][10][11][12]}

Symptoms

People who have misophonia are most commonly angered by specific sounds, such as lip-smacking, slurping, throat-clearing, nail-clipping, chewing, drinking, tooth-brushing, breathing, sniffing, talking, sneezing, yawning, walking, gum-chewing or popping, laughing, snoring, swallowing, gulping, burping, clicking dentures, typing, coughing, humming, whistling, singing, certain consonants, or repetitive sounds.^[13][14] Sufferers experience fight/flight symptoms such as sweating, muscle tension, and quickened heartbeat. Some are also affected by visual stimuli, such as repetitive foot or body movements, fidgeting, or movement they observe out of the corners of their eyes. Intense anxiety and avoidance behaviour often develops, which can lead to decreased socialization. Some people feel the compulsion to mimic what they hear or see.^[15] Mimicry is an automatic, non-conscious, and social phenomenon. It has a palliative aspect, making the sufferer feel better. The act of mimicry can elicit compassion and empathy, which ameliorates and lessens hostility, competition, and opposition. There is also a biological basis for how mimicry reduces the suffering from a trigger.^[6]

Individual reports of extreme emotions in response to triggers have been empirically validated by measuring the skin conductance of misophonic individuals exposed to sustained trigger stimuli.^[1] Skin conductance began increasing 2 seconds after trigger onset and continued to increase for the duration of the trigger.

Prevalence and comorbidity

The prevalence of misophonia is unknown, but groups of people identifying with the condition suggest it is more common than previously recognized.^[15] Among patients with tinnitus, which is found at clinically significant levels in between 4 and 5% of the general population,^[16] some surveys report prevalence as high as 60%,^[15] while prevalence in a 2010 study was measured at 10%.^[17] A 2014 study of students, conducted at the University of South Florida found that 20% of the almost 500 participants had misophonia-like symptoms.^[18] Misophonia may be associated with both depressive and anxiety (particularly obsessive-compulsive) disorders.^[18]

The Dutch study published in 2013^[5] of a sample of 42 patients with misophonia found a low incidence of [co-morbid] psychiatric disorders, with the exception of obsessive–compulsive personality disorder (52.4%).

It has been suggested that there is a connection between misophonia and synesthesia, a neurological condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.^[19] The basic problem may be a pathological distortion of connections between various limbic structures and the auditory cortex, causing sound-emotion synesthesia.^[20] There are people with both misophonia and synesthesia.

Research

In 2015, Duke Medicine released this statement about misophonia:

Misophonia research is in its infancy. There are less than 20 studies that directly evaluate Misophonia. Much of the existing research has not interpreted individual findings on Misophonia to important and related basic and applied research across disciplines. As such, we believe a more comprehensive approach to the study of Misophonia is needed that includes researchers, methods, and measures used across fields (e.g., occupational therapy, audiology, neurology, psychiatry, psychology, cognitive neuroscience, neurobiology). A multi-disciplinary approach to research on Misophonia has the promise to offer insights about the causes and treatments for this condition.^[21]

Treatment

There are a limited number of journal articles and conference reports on treatment for misophonia, none of which involve controlled studies. The most widely used treatment is to add noise to the patient’s environment.^[9][22] With increased ambient noise, many misophonia sufferers hear fewer trigger sounds and thus have fewer trigger responses. Noise can be added to an environment with a sound generator or fan, or directly to the ear with a behind-the-ear sound generator that looks like a small hearing aid. There are two treatment protocols that use sound generators.

The Misophonia Management Protocol^[22] uses the ear-level noise generator and recommends 6–12 weeks of cognitive behavioural therapy or similar therapy for dealing with misophonia as a chronic condition. On average this treatment reduces the perceived severity of misophonia from severe to moderate or moderate to mild, according to patient report. There is no follow-up data.

The second treatment that uses sound is Tinnitus Retraining Therapy.^[9] This treatment uses ear-level noise generators, counselling, and gradual exposure to triggers. This was reported to have produced significant short-term reduction in the severity of misophonia in 83% of the 182 patients treated.

There are two case-study journal articles that report successful reduction of misophonia using cognitive behavioural therapy (CBT). One case was an adult woman whose symptoms were reduced so there was no impairment of social functioning at the end of treatment and for four months post-treatment.^[23] Another was two adolescents who were successfully treated with CBT, but no follow-up data was provided.^[24]

Two case studies of a counter-conditioning treatment reported a reduction in the severity of misophonia.^[11] This treatment is effective only for people who have a small number of triggers from a single person or in a single setting.

There are anecdotal reports of reduction of misophonia symptoms with other treatment methods, but so far no peer-reviewed articles on other methods.

See also

• Hyperacusis
• Phonophobia
• Tinnitus
• Sensory processing disorder
• Chalkboard scraping

References