What Predicts Speech Development in Young, Minimally Verbal Children with ASD?

Saturday, May 14, 2016: 2:52 PM
Room 307 (Baltimore Convention Center)
P. Mirenda1, I. M. Smith2, E. Duku3, P. Szatmari4, S. E. Bryson5, E. Fombonne6, T. Vaillancourt7, J. Volden8, L. Zwaigenbaum9, S. Georgiades3, T. Bennett3 and M. Elsabbagh10, (1)University of British Columbia, Vancouver, BC, Canada, (2)Dalhousie University / IWK Health Centre, Halifax, NS, Canada, (3)McMaster University, Hamilton, ON, Canada, (4)Centre for Addiction and Mental Health, Toronto, ON, Canada, (5)Dalhousie University, Halifax, NS, Canada, (6)Oregon Health & Science University, Portland, OR, (7)University of Ottawa, Ottawa, ON, Canada, (8)University of Alberta, University of Alberta, AB, Canada, (9)University of Alberta, Edmonton, AB, Canada, (10)McGill University, Montreal, PQ, Canada
Background:   Current estimates are that 10%-30% of children with autism are minimally verbal (MV); that is, they fail to acquire spoken language beyond a minimal level by the time they enter school, despite access to early intervention (Kasari, 2013). Past research suggests that nonverbal IQ (NVIQ), ASD severity, imitation skills, and/or joint attention skills at the time of diagnosis predict language outcomes in general (Ellis Weismer & Kover, 2015; Norrelgen et al., 2014; Thurm et al., 2014). However, no study to date has examined the extent to which changes in these variables are predictive of outcomes in children who are MV at the time of diagnosis.

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.