Restricted Interests and Repetitive Behaviors Behavior As a Distinguishing Feature of Autism Spectrum Disorder (ASD) in Nonverbal Children
Differentiating ASD from other developmental disorders can be particularly difficult among nonverbal patients (NV).
To explore diagnostic accuracy and autism symptom profiles of nonverbal children with ASD (ASD-NV) in a large autism registry.
Fifty-five ASD-NV children ages 6-17 years were recruited from a large, voluntary ASD registry. Participants had a confirmatory score >=12 on the Social Communication Questionnaire (SCQ)-Lifetime. Nonverbal status was determined by a “no” response to the SCQ-Lifetime question: “Is she/he now able to talk using short phrases or sentences?” Participation was limited to one of four US geographic regions so participants could receive an in-person ASD assessment and cognitive testing. Parents completed online questionnaires -- Social Responsiveness Scale (SRS); Adaptive Behavior Assessment System-Second Edition (ABAS-II); Repetitive Behavior Scale, Revised (RBS-R) -- and produced evidence their child had received a community ASD diagnosis. Parents asked a teacher to complete an SRS on their child. Data were compared via ANOVA and post-hoc tests with ratings of 108 verbal ASD (ASD-V) children enrolled in a university-based ASD research program at one of the sites. ASD-V children were split into higher-functioning (ASD-V-HighSoc; n = 75) and lower-functioning (ASD-V-LowSoc; n = 33) based on Vineland-II Adaptive Behavior Scale Socialization Domain score of >=70 and <70, respectively.
All 55 ASD-NV children were judged by clinicians to meet criteria for ASD (CI95: 0.935-1.00), and all met ASD cut-offs on both the ADI-R and the ADOS. All exhibited low adaptive functioning at the floor of the ABAS-II, and cognitive functioning was either untestable or at the floor of the selected test(s).
RBS-R: The RBS-R was scored according to the Lam/Aman five-factor solution and scores compared across the three groups controlling for age and sex. There were no statistically significant differences across the three groups for “Ritualistic/Sameness Behavior” and “Restricted Interests.” There were no statistically significant differences across ASD-NV and ASD-V-LowSoc for “Self-Injurious Behavior” and “Compulsive Behavior”; however, both lower-functioning groups more prone to such behaviors than the ASD-V-HighSoc group [F(4,156)=7.086, p<.000 and F(4,156)=4.392, p<.002, respectively]. “Stereotypic Behavior” presented a unique pattern whereby there were statistically significant differences between each group [F(4,156)=21.205, p<.000], with increased presentation of stereotypies corresponding with lower functioning [ASD-NV=11.8(4.88) >ASD-V-LowSoc=7.3(5.12)>ASD-V-HighSoc=5.2(3.99)].
Composite indices of Restricted Interests and Repetitive Behavior (RRB): There were no statistically significant differences across groups for ADI-R Repetitive Behavior. SRS-Teacher Report RRB T-Scores (higher is more severe) were inversely related to level of functioning [F(3, 132)=24.810, p<.000; ASD-NV=90.1.8(12.25) >ASD-V-LowSoc=81.6(17.08)>ASD-V-HighSoc=71.4(12.79)]. SRS-Parent Report RRB T-Scores were comparable for ASD-NV and ASD-V-LowSoc, and both higher than ASD-V-HighSoc [F(3, 157)=11.242, p<.000; ASD-NV=84.2 (10.6) <>ASD-V-LowSoc=87.1 (10.47)>ASD-V-HighSoc=76.8 (11.29)].
See Table 1.
ASD-NV children with community diagnoses of ASD met formal diagnostic criteria for ASD and share Restricted Interests/Repetitive Behavior characteristics with ASD-V children, with severity of such characteristics – both composite and at the factor-level – either comparable or greater than those of ASD-V children. Further research may be valuable in determining whether such Restricted Interests/Repetitive Behavior characteristics may be useful in distinguishing ASD-NV children from NV children with other development disorders.
See more of: Sensory, Motor, and Repetitive Behaviors and Interests