The Social Attention and Communication Study: A School Age Follow-up

Background:  The ability to identify and diagnose Autism Spectrum Disorder (ASD) at increasingly earlier ages offers the opportunity to track their development from toddlerhood. Few longitudinal studies are available that follow children with ASD to school age. The current longitudinal investigation focused on the cognitive development of a cohort of children diagnosed with ASD at 24 months.  

Objectives: The overall objective of this study is to explore the continuity and change in each child's cognitive profile from toddlerhood through to middle childhood. An additional aim is to chart severity of ASD symptoms at each of the time points (24-months, 48-months and 7-9 years) and to investigate diagnostic status at school age using the Autism Diagnostic Observation Schedule (ADOS).

Methods: Thirty five children aged between 7 and 9 years comprise the sample, with each child previously assessed at 24- and 48-months of age using the Mullen Scales of Early Learning (MSEL). The Wechsler Abbreviated Scale of Intelligence (WASI) was administered at their school age follow-up. The ADOS was also administered at all three time points to ascertain diagnostic status and determine severity of ASD symptoms 

Results: Preliminary calculations of data collected thus far reveal that at 24-months, 65% of children tested with a Developmental Quotient (DQ) < 70 on the MSEL, evidencing a developmental delay. At the 48-month follow-up, 40% of children had a DQ < 70. The school age follow-up reveals that the incidence of intellectual disability (Intellectual Quotient < 70) is only 8%. All 35 children met diagnostic criteria for ASD at 24-months and 48-months on the basis of the ADOS algorithm cut-off.  To investigate changes in severity of ASD symptoms over time, Mean ADOS severity scores have been calculated at each time point: 24-months (M=6.21), 48-months (M=5.54) and at school age between 7 and 9 years (M=6.25).  

Conclusions: Preliminary conclusions reveal that many children with ASD have made substantial cognitive gains over time; however, the severity of their ASD symptomatology has remained relatively stable from 24-months through to school age. The improvements in IQ may be due to early detection and subsequent access to intervention earlier in the developmental course. Charting children’s trajectories provides a greater understanding of the rate and pattern of cognitive development in a cohort of children with ASD from toddlerhood to middle childhood. Additionally, these findings provide an understanding of how the symptom profile of ASD presents at different stages throughout childhood.