Background: Few studies have examined the variability in intervention outcomes of very young children with ASD.
Objectives: which child characteristics affect progress with intervention?
Methods: 79 children (mean age: 25.6, SD=4.2 months ), meeting the cut-off points for autism on the ADI, were assessed at pre and post one year of intervention in center-based early intervention programs. Autism severity, cognitive and adaptive skills were measured by standardized tests [Mullen; Vineland; Autism Diagnosis Observation Schedule (ADOS)].
Results: Significant improvement was documented in: autism severity -ADOS scores in all domains (p<.001); cognitive abilities -Mullen standard scores: Visual perception (p<.05), Receptive and Expressive Language (p<.001); adaptive skills- Vineland scores in all domains, p<.001). Correlations between pre-intervention (PRI) autism severity and progress in expressive language and visual domains were significant (p<.01). No significant correlation was found between the PRI cognitive ability and the pre-post-intervention change in autism severity. Comparing PRI autism severity of children that mostly improved (upper third) in expressive language and visual domains with children that improved the least (lowest third), revealed that ADOS scores of the better group were significantly lower (p<.01). No significant differences were found in the PRI cognitive ability between the group that mostly or least improved in their autism severity (ADOS). Regarding cognitive profiles, [verbal/non-verbal (V/NV)], the V>NV group (n=9) had better PRI reciprocal-social scores and significantly better pre-post-intervention improvement in this domain than the V=NV (n=33) and V<NV (n=25) groups (p<.05). Age effect: children that improved the most in pre-post ADOS scores were significantly younger (M=24.5, SD=4.1) than those who less improved (M=27.2, SD=4.2).
Conclusions: Autism severity, cognitive and adaptive skills improve significantly with intervention in young children with ASD. PRI characteristics in social skills and overall autism severity affect post-intervention cognitive outcome. PRI age and cognitive profiles are related to post-intervention change in autism symptoms.