Variability in outcome for children with an ASD diagnosis at age 2

Turner LM and WL Stone

Journal of Child Psychology and Psychiatry. 2007; 48(8): 793-802.

Question: Why do some children diagnosed with ASD at age 2 have a different diagnosis at age 4?

Background: Some children with autism seem to get much better over time. It appears that young children diagnosed now seem to have better outcomes than children who were diagnosed 20 years ago. Knowing why this is so could help parents understand how well their child is likely to do, and figure out which of many interventions is appropriate for individual children.

Design: Follow-up study.

Setting: University-based research centre.

Participants: Forty-eight 2-year-old children, 38 diagnosed with autism and 10 diagnosed with PDDNOS.

Main Outcome Measures: Cognitive ability was assessed using the Mullen Scales of Early Learning; diagnosis was made using the ADOS-G and the ADI-R (for the 4 year olds) and through a clinical examination made by a psychologist. Symptom severity was determined using the Childhood Autism Rating Scale (CARS).

Main Results: At age 4, only 68% of the 38 children diagnosed with autism at age 2 retained that diagnosis.. Of the 10 children with a diagnosis of PDDNOS at 2 years, only 40% retained the diagnosis at age 4. Twelve of the 48 children were no longer on the autism spectrum. All but 1 of those children had either a developmental delay or language impairment, or both.

Conclusions: This study used strict ASD diagnostic methods and appropriate testing for children aged 2 and 4. At age two, the children whose diagnosis changed had less severe autistic symptoms, particularly in the area of reciprocal social interaction, and had higher measures of general intelligence, and were less than 30 months of age at the time of initial evaluation. The latter finding was most likely to predict change of diagnosis by age 4.