What Predicts Speech Development in Young, Minimally Verbal Children with ASD?
Objectives: The purpose of this study was to examine the extent to which NVIQ, ASD severity, imitation and joint attention skills at diagnosis, and changes in imitation and joint attention over the first 6 months thereafter predict verbal status of children with ASD who were MV at diagnosis.
Methods: Data were drawn from the Canadian Pathways in ASD study and included only children who were MV at the time of diagnosis (T1) and for whom the data required to assess verbal status at age 6 were available. Participants were 91 children (89% males) from five Canadian provinces (mean age at T1 = 33.7 mo; range = 19-55 mo). MV status at diagnosis was established by research-reliable assessors using two criteria: (a) code of 1 or 2 on question 30 (Q30) of the Autism Diagnostic Interview-Revised (ADI-R), and (b) code of 3 or 8 on Module 1 of the Autism Diagnostic Observation Schedule (ADOS). At T1, the Merrill-Palmer-Revised Scales of Development was used to measure NVIQ, and the Multidimensional Imitation Assessment (MIA) and Early Social Communication Scales (ESCS) were used to measure imitation and joint attention, respectively. In addition, 66 children completed the MIA and ESCS six months after T1 (T2), and all children were re-assessed with the ADI-R and ADOS at age 6 (T3). Verbal status at T3 was established based on ADI-R Q30 and the ADOS Module completed at that time. Correlation and multinomial regression analyses were conducted to examine the predictors of verbal status at T3.
Results: Of the total sample (N=91), 37.4% remained MV at age 6, 16.5% had words but not phrases, 27.5% had phrase speech, and 18.7% had fluent speech. Neither MIA or ESCS scores at T1 predicted verbal status at T3; the only significant predictor was T1 NVIQ. For the subsample (n=66), MIA Total change scores and ESCS Responding to Joint Attention change scores from T1-T2 were directly related to higher verbal status at T3.
Conclusions: NVIQ at the time of diagnosis and gains in imitation skills and responding to bids for joint attention during the first six months post-diagnosis (associated for many with the onset of early intervention) predicted verbal status at age 6. These results might be useful to guide decision-making related to the effectiveness of early interventions designed to support speech development in young children who are MV at diagnosis.