Deconstructing the Repetitive Behavior Phenotype in Autism Spectrum Disorder through a Whole-of-Population Analysis

Poster Presentation
Friday, May 3, 2019: 11:30 AM-1:30 PM
Room: 710 (Palais des congres de Montreal)
M. Uljarevic1, M. N. Cooper2, K. Bebbington3, E. J. Glasson3, M. T. Maybery4, K. J. Varcin3, G. A. Alvares3, J. Wray5, S. R. Leekam6 and A. O. Whitehouse2, (1)Department of Psychiatry and Behavioral Sciences, School of Medicine, Stanford University, Stanford, CA, (2)Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia, Perth, Australia, (3)Telethon Kids Institute, University of Western Australia, Perth, Western Australia, Australia, (4)School of Psychological Science, University of Western Australia, Perth, Australia, (5)State Child Development Service, Western Australia Department of Health, Perth, Western Australia, Australia, (6)School of Psychology, Cardiff University, Cardiff, NSW, United Kingdom
Background: Restricted and repetitive pattern of behaviors (RRB) are a cardinal feature of autism spectrum disorder (ASD), but there remains uncertainty about how these diverse behaviors vary according to individual characteristics. Firm findings in large, well characterized, heterogeneous cohorts are essential in order to advance the ASD research agenda. Therefore, the current study aimed to enhance our understanding of RRB by utilizing a unique repository of clinical data from the Western Australian (WA) Register for Autism Spectrum Disorders-a long-term prospective, population-based register of newly diagnosed cases of ASD.

Objectives: To characterize the nature of the relationship between Repetitive Motor Behaviours (RMB), Rigidity/Insistence on Sameness (IS) and Circumscribed Interests (CI) with other individual characteristics in newly diagnosed individuals with ASD

Methods: Participants (N= 2668; 18.1% females; Mage= 7.2 years [SD= 4.8]) were part of the Western Australian (WA) Register for ASD, an independent, prospective collection of demographic and diagnostic data (diagnosticians rate each of the DSM-IV-TR criteria on a 4-point Likert severity scale) of newly diagnosed cases of ASD in WA.

Results: The associations between RRB domains, indexed by Kendall’s Tau, were weak, ranging from 0.00 for both CI and IS to 0.20 for IS and RMB. An older age at ASD diagnosis was associated with a lower rating for CI (OR 0.97; 95% CI 0.95,0.98) but a higher rating for IS (OR 1.05; 95% CI 1.03,1.07) and RMB (OR 1.07; 95% CI 1.05,1.09). Higher IQ was associated with lower CI (OR -3.88; 95% CI -5.26,-2.50) but higher IS (OR 3.52; 95% CI 2.13,4.91) and RMB (OR 0.55 95% CI 0.4 0.74). Male gender was associated higher RMB but not IS or CI. Higher social impairments were a significant predictor of higher severity of all three RRB domains; communication severity was a significant predictor only for CI.

Conclusions: The pattern of associations identified in this study provides suggestive evidence for the distinctiveness of RMB, IS, and CI, suggesting the potential utility of RRB domains for stratifying the larger ASD population into smaller, more phenotypically homogenous subgroups that can help to facilitate efforts to understand diverse ASD etiology and inform design of future interventions.