Development of Two New Dimensional Measures of Restricted and Repetitive Behaviors in Parents and Children

Objective: Restricted and repetitive behaviors (RRBs) are a heterogeneous set of behaviors common across a wide range of neurodevelopmental (NDD) and neuropsychiatric disorders (NPD) that extend well into the general population. We introduce two dimensional measures of RRBs for use in both typical and clinical populations from infancy to adulthood. Method: The Childhood Routines Inventory-Revised (CRI-R) and the Adult Routines Inventory (ARI) were created and administered online to a nationality representative cohort of 3,108 parents with 3,032 children (range 12 months – 17 years; 11 months). Twenty-six percent of children and thirty six percent of adults had one or more NDDs/NPDs. Results: Principal axis factoring exploratory analysis revealed a two-factor structure for both instruments (Motor Behaviors/Compulsions and Rigidity/Insistence on Sameness). Analyses for convergent and discriminant validity, internal consistency (Cronbach α ≥ .94), and test-retest reliability (r ≥ .87) all indicated strong psychometric properties. Item response theory (IRT) analyses indicated strong reliability across the score range for both instruments. RRB rates varied across development, peaking between the preschool and school years. Children with NDD/NPDs (particularly those with autism spectrum disorder [ASD], schizophrenia/bipolar, obsessive-compulsive disorder [OCD]/tic disorders) had elevated RRBs relative to those with no diagnosis. Parent–child (.69-.84) and sibling–sibling (.76-.87) intraclass correlations indicate high heritability. Children of parents with an NDD/NPD exhibited more RRBs relative to children of parents without NDD/NPDs. Conclusion: The CRI-R and ARI are open-source instruments with excellent psychometric properties, and will be useful for developmental, clinical, and family genetic studies, as well as for the identification of prodromal conditions involving RRB. The study describes the development, factor structure, and psychometric properties of two new dimensional measures of RRBs across the lifespan. We have refined and expanded an existing quantitative measure of RRB in children, the Childhood Routines Inventory, 7 to encompass the full spectrum of RRBs, including stereotypies, self-injurious behavior, tics, compulsions, habits, sensory sensitivities, and focused interests. Modelled on the CRI-R but adjusted to reflect the adult period of development, we created and normed the Adult Routines Inventory (ARI). Our sample was ascertained from a representative population-based cohort and included individuals both with and without NDD/NPDs, consistent with epidemiological estimates of the frequency of psychiatric disorders in the US 31,32 , and ranging from infancy to older adulthood. Responsiveness Scale–2 (SRS-2). Findings revealed significant overlap between the CRI-R and ARI with the SRS-2, while also revealing substantial unshared variance. Although there were moderate to high correlations between the ARI and CRI-R scales and the SRS-2 subscales, the strengths of these relationships were highest between the RIS and RSMB ARI/CRI-R subscales and the two RRB subscales of the SRS-2, relative to the three SRS-2 subscales that reflect social-communicative and social-emotional traits. We also found distinct patterns of CRI-R/ARI total scores and subscale scores across different NDDs/ NPDs. Together, this suggests that the CRI-R/ARI subscales tap specific patterns of behaviours, rather than simply reflecting global distress or psychopathology, per se. The CRI-R and ARI also provide a more comprehensive assessment of a wider range of RRBs that appear in a range of NDD/NPD than does the SRS, which primarily measures RRBs linked to ASD. However, future research will help determine clinically relevant thresholds on the CRI-R/ARI subscales, and will provide validation of these instruments in different clinical cohorts. Furthermore, in future research, it will be important to explore the performance of the ARI/CRI-R against other RRB measures, including the RBQ-2 and RBQ-2A 8 and the Y-BOCS. 22