Many children with autism spectrum disorder (ASD) overreact to auditory stimuli. Parents of these children are well aware of this problem. Now, UCLA researchers have discovered that these children have brains that react differently than those with ASD who do not respond so severely to noises, visual stimulation, and physical contact. The condition is known as sensory over-responsivity (SOR). The findings, which were published online in the peer-reviewed journal JAMA Psychiatry, could lead to interventions that could benefit more than 50% of individuals with ASD who have SOR.
Interventions for this condition could significantly improve the lives of children with this form of ASD and their families, explained first author Shulamite A. Green, a postdoctoral fellow in the Semel Institute for Neuroscience and Human Behavior at UCLA. He said, “This condition is distressing and impairing for individuals on the autism spectrum, as well as for their parents, who often feel confined to their homes because it’s too difficult to take their children out shopping, to the movies or to a restaurant. Our research provides new insights into the brain differences that may cause sensory over-responsivity, which helps us understand how to treat it – from simple interventions like limiting exposure to multiple sensory stimuli to more complex interventions like cognitive-behavioral therapy.”
Dr. Green noted that SOR research, and particularly brain imaging research, is still very new and sensory symptoms were just recently added to the diagnostic criteria for ASD. He explained that the two developments may ultimately lead to the reasons these children have such strong reactions to sensory stimuli. “One surprise finding was the large differences in brain response between youth with ASD who have SOR and those who do not,” explained senior author Mirella Dapretto, a professor of psychiatry and biobehavioral sciences in the Semel Institute for Neuroscience and Human Behavior at UCLA. She added, “Youth with ASD who do not have SOR have brain responses to sensory stimuli much more similar to their typically developing counterparts without ASD, and we showed that there may be a compensatory mechanism in the brain helping them regulate their responses.”
The study entailed imaging brain responses to auditory and tactile stimuli in children and teens, aged 9 to 17, with and without ASD. During imaging, the children were exposed to three types of sensory stimuli: hearing loud environment noises such as traffic, being rubbed on the inner arm with a scratchy wood fabric, and experiencing both the auditory and tactile stimuli simultaneously.
The investigators found that the children with ASD and SOR had stronger brain responses to the sensory stimuli in brain areas that process sensory information, the primary somatosensory and auditory cortices, as well as in the amygdala, one of the brain’s emotional centers. The brain responses were even more severe when participants with ASD and SOR were exposed simultaneously to both auditory and tactile stimuli. They also found that all the children had a similar initial brain response to the stimuli; however, when they compared the responses of children with both ASD and SOR to children who had ASD but not SOR, the participants with ASD and SOR were much slower in adapting to, and reducing their responses, to the stimuli.
Dr. Green suggested that children with ASD but not SOR may be compensating through strong brain connectivity between their prefrontal cortex and amygdala, an area involved in attention, response to threat and emotional reactions. He explained that the prefrontal cortex is helping to regulate the strong response of the amygdala.
“We don’t have many good treatments for SOR, but our results suggest that an effective treatment might focus on creating coping skills to deal with stimulating environments rather than focusing on changing sensory processing,” noted Dr. Green. He added, “I also think parents and others working with kids with autism need to be aware of their sensory environments. For example, a child might have more trouble being touched in a loud, crowded room. Or if a child has tactile sensitivity, parents may want to be particularly careful that they are wearing comfortable clothing before trying out a new environment, such as a movie theater or restaurant.”
ASD is a neurodevelopmental disability that can cause significant social, communication, and behavioral challenges. It occurs in all racial, ethnic and socioeconomic groups; however, it is almost five times more common among boys than among girls. The Centers for Disease Control (CDC) estimates that about 1 in 68 children suffer from ASD.
