Sensory processing and stereotypical and repetitive behaviour in children with autism and intellectual disability

Background: Sensory processing disorders have been linked to stereotypical behaviours in children with intellectual disability (ID) and autism spectrum disorders (ASD) and to anxiety in children with ASD. In earlier phases of this study with the same participants, we found that those with both ASD and ID were more motivated than those with ID alone to engage in stereotypical behaviour to alleviate anxiety. In this phase, we confirmed that children with both ASD and ID and those with ID alone process sensation differently than typically developing children. We asked: Do the sensory processing difficulties of children with ASD and ID differ significantly from those of children with ID alone in a way that would help explain the increased anxiety of the former group? Method: Parents of children with ASD and ID (n = 29; mean age 9.7 years) and with ID alone (n = 23; mean age 9.5 years) completed a Sensory Profile (SP) to provide information about their children's sensory processing abilities. SP quadrant scores for each group were compared with each other and with the published norms of typically developing children. Results: Children with ASD and ID and with ID alone processed sensory information differently than typically developing children (P = 0.0001;d = > 2.00). Children with both ASD and ID were significantly more sensitive (P = 0.007;d = 0.70) and avoidant (P