19948
Repetitive and Restricted Behaviours in the General Population: Validation and Heritability of Two New Instruments for Parents and Children
Objectives:
- To validate and extend a measure of RRBs in a large, nationally representative United States sample of parents and their children
- To explore the heritability of these RRBs through parent-child intraclass correlations
Methods: Three thousand one-hundred eleven parents (31.1% male, 68.9% female; M age=38.15 years, SD= 9.95) completed the Adult Routines Inventory (ARI), a newly developed 55-item questionnaire about their own RRBs. Parents also completed the Childhood Routines Inventory-Revised (CRI-R), a 62-item questionnaire about their children’s repetitive behaviours. Children ranged in age from 1 year to 17 years, 11 months (M=9.29 years, SD= 4.82).
Results: Exploratory factor analysis (Maximum Likelihood with oblique rotation) yielded the following two factors for both the ARI and CRI-R: Rigidity/Insistence on Sameness (RIS) and Motor Stereotypies/Compulsions (MSC). Indices of skewness and kurtosis revealed normal distributions of both measures. Internal consistency and test-retest reliability for both scales for both ARI and CRI-R was excellent (Cronbach α≥ .92). The association between repetitive behaviours in children and parents was examined with the intraclass correlation coefficient (ICC). ICC for Rigidity/Insistence on Sameness was 0.73 (p< 0.0001) and for Motor Behaviours/Compulsions was 0.83 (p< 0.0001). CRI-R data were available for 844 sibling pairs (mean age= 7.99 years; SD= 4.14; 51.5% male, 48.5% female). ICC for Rigidity/Insistence on Sameness was .75 (p< 0.0001) and for Motor Behaviours/Compulsions was .85 (p< 0.00001).
Conclusions: This study introduced two RRB instruments suitable for use in both neurodevelopmental disorders and in studies of normative development, across the lifespan. We report their validity and reliability based on a large nationally-representative sample. Parent-child ICCs suggest high heritability. These measures will be useful for family studies as well as for studying children who are at risk and/or who may exhibit sub-clinical or prodromal symptoms reflecting a wide range of neurodevelopmental disorders characterized by RBBs.