Children with autism spectrum disorder all have atypical brain responses to sensory stimuli, but top-down regulatory mechanisms influenced whether or not they expressed atypical behavioral responses, according to a study published in the American Journal of Psychiatry.

The study included 42 children and adolescents with ASD (21 with high levels of sensory over-responsivity [SOR]; 21 with low levels of SOR) and 27 age-matched control participants (mean age, 13.7 years). Investigators assessed the 3 groups on initial brain response to joint (auditory and tactile) stimuli, habituation (change over time), and generalization of response to novel stimuli using functional magnetic resonance imaging in the amygdala and the somatosensory, auditory, visual, and prefrontal cortices. They also assessed the relationship among SOR and amygdala-frontal functional connectivity changes across exposure to the joint stimuli.

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There were no significant differences between groups in initial response to joint stimuli. Participants with ASD who had high levels of SOR showed decreased ability to maintain habituation in the amygdala and relevant sensory cortices and inhibition of irrelevant sensory cortices across repeated sensory stimulation. Participants with ASD who had low levels of SOR showed decreased responsiveness to new but similar stimuli and increased prefrontal-amygdala regulation. Post hoc analyses revealed that participants with high levels of SOR showed initial but unsustained amygdala-prefrontal connectivity, and participants with low SOR switched from positive to negative amygdala-prefrontal connectivity across sensory exposure. There were no significant changes in connectivity among participants in the control group.

“Taken together, our results indicate that in ASD, sensory habituation is a dynamic, time-varying process dependent on sustained regulation across time, which is specifically impaired in children and adolescents with ASD with high SOR. However, those with ASD with low SOR also show distinct, nontypical response patterns, including increased prefrontal regulation and reduced reactivity to new stimuli,” stated the investigators. They concluded that further research could focus on personalized interventions, including exposure therapy.

Reference

Green SA, Hernandez L, Lawrence KE, et al. Distinct patterns of neural habituation and generalization in children and adolescents with autism with low and high sensory overresponsivity [published online June 24, 2019]. Am J Psychiatry. doi:10.1176/appi.ajp.2019.18121333