Non-verbal IQ and change in restricted and repetitive behavior throughout childhood in autism: a longitudinal study using the Autism Diagnostic Interview-Revised

Pathways Team

Research output: Contribution to journalArticlepeer-review

14 Citations (SciVal)


Background: Restricted 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. Methods: The 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. Results: The 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. Limitations: The 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. Conclusions: These 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.

Original languageEnglish
Article number57
JournalMolecular Autism
Issue number1
Publication statusPublished - 14 Aug 2021

Bibliographical note

Funding Information:
Authors acknowledge funding by: The Azrieli Centre for Autism Research (ACAR), The Canadian Institutes of Health Research, Fonds de Recherche du Québec, Kids Brain Health Network (formerly NeuroDevNet), Autism Speaks (US), Government of British Columbia, Alberta Innovates Health Solutions, and the Sinneave Family Foundation. AP received additional support from the NIHR KCL/South London and Maudsley NHS Foundation Trust Biomedical Research Centre and Senior Investigator Award NF-SI-0617–10120. RB is supported by a King’s Prize Fellowship (204823/Z/16/Z).

Funding Information:
The authors would like to thank Samantha Wunderlich and Myriam Beauchamp for their thoughtful comments and revisions on the manuscript. We would also like to thank Julie Scorah and Mandy Steinman for their help with interpretation of some results and Michelle Dawson for her suggestions of relevant references. Thanks also to the QUIC workgroup for their help throughout the writing of this paper: Rackeb Tesfaye, Nicola Wright, Virginia Carter Leno, Hannah Pickard and Alana McVey. The authors also acknowledge the past and?current members of the Pathways in ASD Study Team, who made equal?contributions to the study. Finally we are extremely grateful to all the families participating in the Pathways in ASD study for their continued engagement in this project.

Publisher Copyright:
© 2021, The Author(s).


  • ADI-R
  • Autism
  • Behaviors
  • Intelligence
  • Interest
  • Longitudinal
  • Repetitive
  • Restricted
  • Wechsler

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Neuroscience
  • Developmental Biology
  • Psychiatry and Mental health


Dive into the research topics of 'Non-verbal IQ and change in restricted and repetitive behavior throughout childhood in autism: a longitudinal study using the Autism Diagnostic Interview-Revised'. Together they form a unique fingerprint.

Cite this