Abstract
BackgroundRestricted and repetitive behavior (RRB) is one of the characteristic features of Autism Spectrum Disorder. This domain of symptoms includes a broad range of behaviors. There is a need to study each behavior individually to better understand the role of each in the development of autistic children. Moreover, there are currently no longitudinal studies investigating change in these behaviors over development.MethodsThe goal of the present study was to explore the association between age and non-verbal IQ (NVIQ) on 15 RRB symptoms included in the Autism Diagnostic Interview-Revised (ADI-R) over time. A total of 205 children with ASD were assessed using the ADI-R at time of diagnosis, at age 6 years, and at age 11 years, and with the Wechsler Intelligence Scales for Children—Fourth Edition (WISC-IV) at age 8 years.ResultsThe proportion of children showing each RRB tended to diminish with increasing age, except for sensitivity to noise and circumscribed interests, where the proportion increased over time. Although there was no significant main effect of NVIQ, there was a significant interaction between age and NVIQ. This was mainly driven by Difficulties with change in routine, for which higher NVIQ was associated with the behavior remaining relatively stable with age, while lower NVIQ was associated with the behavior becoming more prevalent with age.LimitationsThe study focused on the presence/absence of each RRB but did not account for potential changes in frequency or severity of the behaviors over development. Furthermore, some limitations are inherent to the measures used. The ADI-R relies on parent report and hence has some level of subjectivity, while the Wechsler intelligence scales can underestimate the intellectual abilities of some autistic children.ConclusionsThese results confirm that specific RRB are differentially linked to age and NVIQ. Studying RRB individually is a promising approach to better understanding how RRB change over the development of autistic children and are linked to other developmental domains.
Highlights
Restricted and repetitive behavior (RRB) is one of the characteristic features of Autism Spectrum Disor‐ der
In autism it was proposed that some types of behavior that are often labelled as “lower order” RRB would be linked to the lower cognitive level of the child and not specific to autism [11], while others, generally labelled as “higher order’’ RRB may be an inherent part of autistic development [2, 12, 13]
Separate GEE models for each Autism Diagnostic Interview-Revised (ADI-R) item, using a Bonferroni correction for multiple comparisons, showed that this interaction was driven by certain RRB significantly decreasing with age
Summary
Restricted and repetitive behavior (RRB) is one of the characteristic features of Autism Spectrum Disor‐ der. RRB are observed in autistic children of all intelligence levels but they appear to vary in degree depending on age and cognitive level [2, 5] Despite their higher prevalence in autism, RRB are observed in populations diagnosed with other conditions such as intellectual disability, Tourette syndrome, obsessive–compulsive disorder [6,7,8] and in typically developing children [i.e. 6, 7, 9]. In autism it was proposed that some types of behavior that are often labelled as “lower order” RRB would be linked to the lower cognitive level of the child and not specific to autism [11], while others, generally labelled as “higher order’’ RRB may be an inherent part of autistic development [2, 12, 13] The latter reflects manifestations of the way autistics perceive and process information [14, 15]. Similar patterns of development could characterize autistic children with normal intelligence, but more research is needed to disentangle the effects of age and cognitive level on RRB
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