Between 55 and 70 percent of children with autism spectrum disorders (ASDs) experience sensory over-responsivity (SOR), a severe and negative response to, or avoidance of, sensory stimuli such as noisy environments, unexpected loud noises, scratchy clothing or being touched. Children with ASD and SOR have more anxiety, greater functional impairment and poorer social outcomes than those without it. Because SOR has only recently been considered in the diagnostic criteria for ASD, it has not yet been well studied and little is known about brain mechanisms of SOR or how to treat it.
Susan Bookheimer and her colleagues at the University of California, Los Angeles propose to study brain activity using functional magnetic resonance imaging (fMRI) and to assess physiological responses (including galvanic skin response and heart rate) in children with ASD with and without SOR to understand basic mechanisms that cause SOR. Bookheimer and her team will present uncomfortable sounds (white noise) and sensations (itchy fabric) to individuals in the scanner, while measuring both brain and body responses. To differentiate the underlying mechanisms of anxiety and SOR, the team will compare responses in children who have ASD only or ASD and SOR, with children who have anxiety but not ASD, and with typically developing children.
As most treatments for anxiety are based on exposure therapy, the team will also assess basic properties of habituating to uncomfortable sensations by observing whether repeated exposure reduces anxiety reactions in ASD, and whether this exposure will generalize to different uncomfortable sensations. Importantly, preliminary studies from this group suggest that exposure has different effects on the brain in ASD children with and without SOR. Thus it is possible that traditional therapies may be ineffective, and could possibly make children with ASD and SOR worse. Therefore, understanding the effects of exposure and generalization is critically important for developing effective interventions for ASD children with SOR. Finally, by comparing brain activity to external physiological measures that are easily obtained in community settings, the researchers aim to provide results that can be translated into the clinic to aid in the treatment of ASD.