Similar developmental trajectories in autism and Asperger syndrome: from early childhood
The objective of this study was to chart the developmental trajectories of high-functioning
children with autism spectrum disorders (ASD) from early childhood to adolescence
using the presence and absence of structural language impairment (StrLI) as a way
of differentiating autism from Asperger syndrome (AS).
Sixty-four high-functioning children with ASD were ascertained at 4-6 years of age
from several different regional diagnostic and treatment centers. At 6-8 years of
age, the ADI-R and the Test of Oral Language Development were used to define an autism
group (those with StrLI at 6-8 years of age) and an AS group (those without StrLI).
Growth curve analysis was then used to chart the developmental trajectories of these
children on measures of autistic symptoms, and adaptive skills in communication, daily
living and socialization.
Differentiating the ASD group in terms of the presence/absence of StrLI provided a
better explanation of the variation in growth curves than not differentiating high-functioning
ASD children. The two groups had similar developmental trajectories but the group
without StrLI (the AS group) was functioning better and had fewer autistic symptoms
than the group with StrLI (the autism group) on all measures across time. The differences
in outcome could not be explained by non-verbal IQ or change in early language skills.
Distinguishing between autism and Asperger syndrome based on the presence or absence
of StrLI appears to be a clinically useful way of classifying ASD sub-types.
Szatmari P, Bryson S, Duku E, Vaccarella L, Zwaigenbaum L, Bennett T, Boyle MH
Diagnostic and Statistical Manual of Mental Disorders
Severity of Illness Index
Stereotypic Movement Disorder
Research Support, Non-U.S. Gov't