Recently there have been some people who want to redefine misophonia as a form of sensory processing disorder (SPD) or sensory over-responsiveness. I think there are good reasons to not combine misophonia and SPD, and especially not to consider misophonia as a form of SPD. This is confusing to some individuals who have both SPD and misophonia. The disorders are not mutually exclusive. I think it is well-meaning individuals who have both disorders that are promoting they be combined. From their experience, the two disorders combine to create a horrible sensory problem, but the disorders should not be combined because they are distinctively different.
Research on SPD has been underway for at least two decades. It has gained increased attention because children with autism often have sensory issues, and there are generally considered SPD. SPD was considered for inclusion in the Diagnostic and Statistical Manual of Mental Disorders (DSM), release 5, which occurred in 2013. But it was not included in the DSM-5, likely because there is still a strong debate over whether SPD is a real disorder. For instance, see the Scientific American article, Is Sensory Processing Disorder for Real?
SPD includes three broad categories. These are sensory modulation disorder, sensory-based motor disorders and sensory discrimination disorders. Sensory based motor disorders and sensory discrimination disorders do not have symptom similarities to misophonia, so I will not discuss them further.
Sensory modulation disorder appears as a problem with the intensity, duration, or frequency of the stimuli. It includes three categories:
– sensory under-responsivity – not at all like misophonia
– sensory craving/seeking – not like misophonia. People with misophonia avoid trigger stimuli.
– sensory over-responsivity – appears to have similarities with misophonia
Sensory over-responsivity (which I will call SPD from here on for simplicity) shows up as fearful, stubborn (or other negative behaviors), and self-absorbed behavior, in response to strong/loud stimuli. It may also include distress, anxiety, anger, and other strong emotions when exposed to stimuli, especially when the stimulus is prolonged. For example, an SPD child may have a fear response when hearing a toilet flush, but if he is forced to stay close, and there are repeated flushes, his emotions and behavior will escalate. Sometimes the emotions and extreme behavior happen instantly. It is common for children with SPD to have meltdowns. Emotional distress, meltdowns, and negative behaviors are common with misophonia, but with misophonia anger and disgust are the most common emotions. Misophonia occasionally includes a fear response, but never includes self-absorbed behavior. Misophonia also includes anxiety, and children (and even adults) with misophonia often have meltdowns.
One big difference with misophonia and SPD is the age of onset. SPD is generally present at very young ages. It shows as an infant who is upset by a loud toy, or a toddler who is afraid of a vacuum cleaner. One of my grandkids could not tolerate the sound of the toy grill on the playhouse, so I muffled the speaker. Misophonia can develop at any age. About half of those with misophonia had onset by age 10. But misophonia does begin in later years for some. A recent study I conducted shows about 5% of individuals had onset of misophonia as adults, and for some, it did not begin until they were in their 50s.
With both misophonia and SPD, a person has a strong emotional response to auditory, visual, or tactile stimuli, but SPD triggers and misophonic triggers are very, very different. I will discuss this in my next post.