Diagnostic and Developmental Trajectories in Toddlers with ASD

Background:  

Increasing awareness among parents and professionals of early signs of ASD has led to a rise in the number of toddlers referred for a diagnostic evaluation in the second year of life. The question of the stability of social-communicative impairments remains to be clarified, as well as the extent to which the constellation of delays and abnormalities observed in the second year is unique to ASD.  

Objectives:  

To examine developmental and diagnostic trajectories of children evaluated for ASD in the second year and to identify profiles of skills that are predictive of the diagnostic outcome in the fifth year. 

Methods:  

Developmental and social-communication skills of 89 toddlers were assessed at Time 1 (age: M = 21.5 months, SD = 4.9) and Time 2 (age: M = 46.9 months, SD = 7.7) and clinical best estimate diagnosis (CBE) was assigned at both times.  Groups with stable diagnostic presentation (e.g., AUT-AUT; DD-DD) and unstable presentation (e.g., AUT-PDD) were identified and compared on cognitive and social-communication profiles at Time 1.   

Results:  

Diagnostic trajectories from Time 1 to Time 2 were stable in the majority of toddlers with ASD (77%).  In a minority of toddlers initially diagnosed with autism (26%), marked improvements warranted a change in diagnosis at follow-up (AUT-PDD).  While their social behavior at Time 1 was similarly impaired as the AUT-AUT group, they tended to have fewer repetitive behaviors and their overall intentionality of communication was rated as more impaired by experienced clinicians. Cognitive profiles across the diagnostic trajectory groups differed significantly at Time 1.

Conclusions:

Stability of the CBE diagnosis of ASD in the 2^nd year appears satisfactory.  Examination of cognitive profiles can be helpful in making diagnostic distinctions.  In a subgroup of children with ASD, early social dysfunction might be exacerbated by profound impairments in intentional communication.