Investigating the structure of the restricted, repetitive behaviours and interests domain of autism
Version of Record online: 22 SEP 2005
Journal of Child Psychology and Psychiatry
Volume 47, Issue 6, pages 582–590, June 2006
How to Cite
Szatmari, P., Georgiades, S., Bryson, S., Zwaigenbaum, L., Roberts, W., Mahoney, W., Goldberg, J. and Tuff, L. (2006), Investigating the structure of the restricted, repetitive behaviours and interests domain of autism. Journal of Child Psychology and Psychiatry, 47: 582–590. doi: 10.1111/j.1469-7610.2005.01537.x
- Issue online: 26 APR 2006
- Version of Record online: 22 SEP 2005
- Manuscript accepted 1 June 2005
- Pervasive developmental disorders;
- restricted repetitive behaviours and interests;
- principal components analysis;
- structure of autism domains;
- genetic studies
Background: The Restricted, Repetitive Behaviours and Interests (RRBIs) are represented in the DSM-IV and measured by the Autism Diagnostic Interview-Revised (ADI-R) as one of the three homogeneous symptom categories of Pervasive Developmental Disorders. Although this conceptualisation is well accepted in the field, the grouping of symptoms is based primarily on clinical judgment rather than on empirical evidence.
Methods: The objective of this study was to examine the factor structure of the RRBI domain of autism. Eleven items from this domain of the ADI-R were used in a Principal Components Analysis (PCA). Our sample consisted of 339 individuals with a Best Estimate diagnosis of Pervasive Developmental Disorder (PDD).
Results: Findings indicate that the RRBI domain is composed of two distinct factors or dimensions: Insistence on Sameness (IS) and Repetitive Sensory and Motor Behaviours (RSMB). RSMB is negatively correlated with adaptive skills; that is, lower functioning individuals tend to have higher levels of repetitive sensory and motor behaviours. On the other hand, IS is positively correlated with autistic symptoms in the communication and language domain. Further analyses suggest moderate familial aggregation among affected sibling pairs within the IS but not the RSMB factor.
Conclusions: These results provide evidence for the heterogeneity of the RRBI domain of the ADI-R in terms of both clinical presentation and other correlates. In addition, the IS factor seems to be under familial (presumably genetic) control, while RSMB appears to simply reflect variation in developmental level.