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A New Look at Sensory Symptoms in Autism: Is it One or Two?

Marina Sarris
Interactive Autism Network at Kennedy Krieger Institute
Date Published: 
June 14, 2016

Photo of boy staring at a fan, a sensory interest in autismWhat if we're looking at sensory problems in autism the wrong way?

A new study suggests that children may have two different and unrelated types of sensory problems, not one as currently believed. The study involves families in the Interactive Autism Network (IAN) and the Simons Simplex Collection (SSC).1

Researchers found that sensory interests – a fascination with a whirling fan or flickering lights, for example – should be considered as separate from sensory sensitivities, such as unusual reactions to noise, texture, smell, touch, temperature, or other input from one's senses.1 Children with sensory sensitivities may overreact to their senses, by covering their ears when they hear common sounds. Or, they may underreact, by appearing to be deaf, for instance.

Currently, sensory interests and sensitivities are combined into one category of autism symptoms. But if they were really so similar, shouldn't children who have sensory interests be much more likely to have sensory sensitivities, and vice versa?

That's one of the questions asked by researchers Thomas W. Frazier, PhD, and Antonio Y. Hardan, MD. They analyzed survey responses from parents of more than 2,600 children with autism in the SSC and 3,900 children with autism in IAN Research. Both SSC and IAN families completed the Social Responsiveness Scale. In addition, IAN parents answered the Social Communication Questionnaire and SSC families completed the Repetitive Behavior Scale-Revised.

The researchers did not find a strong overlap between sensory interests and sensitivities. That suggests that they should be considered and studied separately, Drs. Frazier and Hardan reported.1

In the current manual used to diagnose autism, however, sensory sensitivities and interests are combined. Together they make up one of the four categories of "restricted, repetitive patterns of behavior" in autism. The categories are:

  • Repeating certain motions and words, such as flapping hands, flicking fingers, or echoing words.
  • Insisting that objects or routines always be the same. A different route to school, for instance, could trigger a meltdown.
  • An obsessive and unusual interest, such as being preoccupied with train schedules or vacuum motors.
  • Sensory sensitivities or interests.2

Children need "at least two" of those four symptoms for a diagnosis, among other things, according to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).2

Looking for better ways to describe autism

... keeping separate things separate just seems like a good idea.

Dr. Frazier, director of the Center for Autism at Cleveland Clinic, said he wanted to examine the accuracy of the way repetitive symptoms are grouped in the DSM-5 manual, which also is used to diagnose many mental conditions.

Photo of boy covering ears, illustrating noise sensitivity in autismDr. Frazier said he did not believe a child would be misdiagnosed based on the current categories of symptoms.

"I think it is unlikely that a child would have both of these [sensory symptoms] and no other symptoms. However, by separating them out, we may improve clinicians' focus on these as separate. Clinicians may spend more time teasing them out. At present, I have seen situations where clinicians say the child did not have any sensory symptoms but what they meant is the child had no unusual sensory interests. They did not assess for sensory sensitivities," Dr. Frazier said in an email.

"Plus, keeping separate things separate just seems like a good idea," he added. A more accurate system for classifying autism symptoms could lead to better tools for diagnosing it in the future, he said.

Although the researchers did not find a strong link between sensory interests and sensitivities, they did find a link between two other symptoms. Children who have repetitive movements, such as finger flicking, are more likely to have unusual sensory interests, such staring at ceiling fans.

Health care providers see this often, Dr. Frazier said. "Children who engage in self-stimulatory behavior also show more repetitive motor mannerisms. Other papers have suggested that these two things go together as well."

Dr. Frazier said he thinks children with both repetitive movements and unusual sensory interests "are more likely to have cognitive impairments or intellectual disability. These children tend to be more affected and are often called 'low functioning.'"

As with all new studies in science, this one will need to be repeated and its findings confirmed to make sure the results are accurate. If that happens, then American psychiatrists should consider separating sensory interests and sensitivities into two different categories when they revise future editions of their DSM manual, the paper concluded.1

The study results were presented at the 2016 International Meeting for Autism Research in May in Baltimore, Maryland.

What do we know about sensory sensitivity?

Other research by the Interactive Autism Network has found that children with noise sensitivities fall into two categories, without much overlap.3 "We found that, among children with auditory sensitivity, there is a divide between children with hypersensitivity, who react strongly to sound, and those with hyposensitivity, who underreact to sounds and noises," said IAN Research Director J. Kiely Law, MD.

Some people seek help for sensory sensitivities that interfere with everyday life, such as may occur when loud noises trigger meltdowns or running away. Some occupational therapists specialize in treating sensory problems common to autism. They may try to help a child organize his sensory input so he can respond more appropriately, and participate in activities that used to bother him. In some clinics and schools, occupational therapists work with speech-language pathologists and behavior analysts to address these problems. For more information on therapy for sensory problems, see the Additional Resources section.

Families and individuals with autism play a critical role in helping researchers and clinicians better understand the disorder. Find out how you can participate in IAN Research.

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References: 
  1. Frazier, T. W. & Hardan, A.W. (2016). Empirically-identified restricted repetitive behavior domains: Informing DSM-6. 2016 International Meeting for Autism Research, Baltimore, Maryland. Abstract
  2. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Association.
  3. Law, J. K., Rubenstein, E., Marvin, A., Toroney, J., & Lipkin, P. H. (2016). Auditory sensitivity issues in children with autism spectrum disorders: Characteristics and burden. Pediatric Academic Societies Meeting; April 30-may 3, 2016, Baltimore, Maryland. Poster: https://iancommunity.org/sites/default/files/galleries/conference-presentations/Law_PAS_2016.pdf