Deconstructing the repetitive behaviour phenotype in autism spectrum disorder through a large population‐based analysis

Abstract

Objective: Restricted and repetitive pattern of behaviours (RRB) are a cardinal feature of autism spectrum disorder (ASD), but there remains uncertainty about how these diverse behaviours vary according to individual characteristics. This study provided the largest exploration to date of the relationship between Repetitive Motor Behaviours, Rigidity/Insistence on Sameness and Circumscribed Interests with other individual characteristics in newly diagnosed individuals with ASD. Method: Participants (N= 3647; 17.7% females; Mage= 6.6 years [SD= 4.7]) were part of the Western Australian (WA) Register for ASD, an independent, prospective collection of demographic and diagnostic data of newly diagnosed cases of ASD in WA. Diagnosticians rated each of the DSM-IV-TR criteria on a 4-point Likert severity scale and here we focused on the Repetitive Motor Behaviours, Insistence on Sameness and Circumscribed Interests symptoms. Results: The associations between RRB domains, indexed by Kendall's Tau, were weak, ranging from non-significant 0.003 for both Circumscribed Interests and Repetitive Motor Behaviours to significant 0.20 for Insistence on Sameness and Repetitive Motor Behaviours.Older age at diagnosis was significantly associated with lower Circumscribed Interests and significantly associated with higher Insistence on Sameness and Repetitive Motor Behaviours. Male sex was significantly associated with higher Repetitive Motor Behaviours but not Insistence on Sameness or Circumscribed Interests. Higher social impairments were a significant predictor of higher severity of only Circumscribed Interests but did not significantly predict other two domains. Conclusion:The pattern of associations identified in this study provides suggestive evidence for the distinctiveness of Repetitive Motor Behaviours, Insistence on Sameness, and Circumscribed Interests, suggesting the potential utility of RRB domains for stratifying the larger ASD population into smaller, more phenotypically homogeneous subgroups that can help to facilitate efforts to understand diverse ASD etiology and inform design of future interventions.

Toward better characterization of restricted and unusual interests in youth with autism

“…Investigations that have measured RI using more general autism severity or RRB measures have reported a positive (S. L. Bishop et al, 2013), negative (Uljarević et al, 2020), and the lack of a significant relationship with IQ (Lam, Bodfish, & Piven, 2008), however, as noted, some of these studies utilized subscales that combined interests atypical in terms of focus, theme, and/or intensity, which could have contributed to the inconsistent findings. There are several possible interpretations of the association between the presence of RIs and IQ status.…”

Camouflaging in Autism: Examining Sex‐Based and Compensatory Models in Social Cognition and Communication

“…With expanding prevalence rates worldwide, a male bias emerges with a male‐to‐female ratio of 4:1 [Maenner et al, 2020]. Evidence suggests the true male‐to‐female ratio may be closer to 2:1 or 3:1 due in part to underdiagnosis of females [Kim et al, 2011; Loomes, Hull, & Mandy, 2017] and a unique phenotype of ASD among females [Kreiser & White, 2014; Mandy et al, 2012; Uljarevic et al, 2020].…”

“…Regarding social cognition, female children with ASD show greater visual attention to faces compared to males with ASD [Harrop et al, 2019]. In the largest cohort of individuals with ASD to date examining restricted, repetitive behaviors and interests (RRB), male sex was associated with more repetitive motor behaviors [Uljarevic et al, 2020]. Some studies report that females without co‐occurring intellectual impairment endorse higher internalizing problems (e.g., anxiety, depression) than males with ASD [Kreiser & White, 2014], similar to well‐documented sex‐based patterns among typically‐developing adolescents and adults [Allgood‐Merten, Lewinsohn, & Hops, 1990; Altemus, Sarvaiya, & Neill Epperson, 2014; Kendler & Gardner, 2014].…”

“…As the previous review illustrates, different definitions and approaches are used to characterize and elucidate the camouflaging construct in the ASD phenotype. Findings from multiple studies on children and adults with ASD suggest a developmental effect to camouflaging [Lai et al, 2012; Livingston, Colvert, et al, 2019; Uljarevic et al, 2020]; yet studies on adolescents are sparse. Given that adolescence is a critical developmental period in which internalizing symptoms and sex‐based differences emerge in typically‐developing youth, the study of camouflage and compensation during adolescence in ASD is vital.…”

Toward better characterization of restricted and repetitive behaviors in individuals with germline heterozygous PTEN mutations

“…When considering the pattern of association within the RMB domain, it is important to note that although this domain was originally considered as indicative of developmental delay (Prior & MacMillan, 1973; Turner, 1999), subsequent empirical studies have provided a more nuanced elaboration of the notion of RMB as “lower‐order” RRB. More specifically, although RMB are indeed characteristic of early normative development, sharply declining after children reach 15 months of age (Uljarević, Arnott, et al, 2017) and tend to be associated with lower IQ in ASD (Bishop et al, 2006; Bishop et al, 2013) and genetic syndromes such as Fragile X syndrome (Oakes et al, 2016), they are nevertheless prevalent among ASD individuals with IQ in the normative range (Richler et al, 2010; South et al, 2005; Uljarević et al, 2020). This is in line with our findings that while higher RMB scores were associated with lower FSIQ across both measures, particularly among PTEN ‐ASD and Macro‐ASD groups, there was still a portion of individuals with PTEN ‐No ASD whose FSIQ was in >70 range who did not show floor level scores in RMB domain.…”