Effortful Control but Not Negative Affectivity Predicts Intensity of Restricted Repetitive Behaviors in Toddlers With Neurodevelopmental Conditions

Objective Restricted repetitive behaviors (RRBs) are prevalent across neurodevelopmental conditions. It has been hypothesized that greater RRB severity reflects elevated distress or diminished regulatory capacity. To test these hypotheses, we examined prospective associations between early negative affectivity (NA) and effortful control (EC) and later RRB severity in a transdiagnostic sample of toddlers with and without autism. Method Participants were 238 toddlers with neurodevelopmental conditions (autism n =165; non-autism n =73). NA and EC were assessed at Time 1 (M age =24.4 months, SD=5.2) using the Toddler Behavior Assessment Questionnaire or the Early Childhood Behavior Questionnaire. At Time 2 (M age =42.2 months, SD=7.3), RRB severity was assessed using the Autism Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview–Revised (ADI-R). Multivariate regression models tested whether Time 1 NA and EC predicted Time 2 RRBs, controlling for age, sex, nonverbal developmental quotient, Time 1 RRBs, and visit year. Results Higher EC at Time 1 predicted lower ADI-R RRB scores at Time 2 ( p <.001) but was not associated with ADOS RRB scores ( p =.621). Higher EC was associated with ADI-R lower intensity of compulsive adherence to nonfunctional routines or rituals ( p =.001), stereotyped repetitive motor mannerisms ( p <.001), and preoccupation with parts of objects or their nonfunctional elements ( p = .002), but not circumscribed interests ( p =.266) items. Time 1 NA was not associated with Time 2 RRBs on either measure. Conclusion Regulatory and affective traits show differential longitudinal associations with RRBs, highlighting a potential role for effortful control in their emergence or maintenance. Interpretation of null findings for negative affectivity is limited by unmeasured early environmental influences on the development of anxiety. Diversity & Inclusion Statement We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper received support from a program designed to increase minority representation in science. We actively worked to promote sex and gender balance in our author group.We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group.