Factor Structure of RRBs in Verbal and Non-Verbal Preschoolers With ASD or Related Characteristics

RRBs are a core symptom domain of autism spectrum disorder (ASD). The DSM-5 defines RRBs across 4 categories, though research supporting these distinct categories has been inconsistent. The purpose of this work is to examine the factor structure of RRBs in Verbal and Non-verbal children with ASD or subthreshold symptoms, and determine child characteristics associated with these factors.

We used data from a second phase of an ongoing study to confirm the factor structure of RRBs on ADI-R items in Verbal and Non-verbal preschool children (mean age = 57.1 months, SD = 8.32), separately. Using multivariable regression, we evaluated the association between Verbal and Non-verbal children factor scores and clinical characteristics using the ADOS, CBCL, and Vineland-2.

A 3-factor structure of RRBs (RSMB; IS; and SPEECH) was confirmed in Verbal children and a 2-factor structure (RSMB and IS) was identified for Non-verbal preschoolers. Higher scores on the ADOS RRB CSS were associated with worse RSMB factor scores in Verbal and Non-verbal preschoolers. Verbal preschoolers with worse internalizing symptoms also had worse RSMB, IS, and SPEECH factor scores. In Verbal and Non-verbal children, worse social adaptive scores were associated with worse RSMB factor scores.

By analyzing Verbal and Non-verbal preschoolers separately, we confirmed the presence of a unique SPEECH factor in Verbal children. This approach indicates that RRBs coalesce in 3 factors (RSMB, IS, and SPEECH) in Verbal youth and 2 factors (RSMB and IS) in Non-verbal youth, a pattern not reflected in the current diagnostic manual.