Thursday, May 20, 2010
Franklin Hall B Level 4 (Philadelphia Marriott Downtown)
While language ability is an important predictor of outcome in children with autism, the role of language among high functioning children with autism spectrum disorders (HF-ASD) is more controversial. Language milestones and current language functioning are key elements of the diagnostic distinction between Asperger Syndrome and high functioning autism. However, disagreement currently exists in the field regarding whether early language milestone attainment and structural language are predictive of later communication and language abilities in high functioning autism. This confusion may in part be due to the definitions used in previous studies examining the impact of language delays. Some studies have relied on the DSM-IV definitions, which are not representative of typical language development. Twenty-four, not 36, months is the accepted milestone for phrase speech and is recommended as a developmental language benchmark by an NIH ASD working group. Milestones are easily obtained and knowledge of their implications for later language abilities would be useful in both clinical and research settings.
In this investigation, we examine whether attainment of typical early language milestones in children with HF-ASD predicts better outcome, as measured by core language abilities and adaptive communication skills, at school age.
Subjects were a clinically referred sample of 77 children (mean age: 9.1 ± 2.8 years; 88.3% male; verbal, nonverbal or full scale IQ≥70) diagnosed with an ASD (autism n=35, Asperger Syndrome n=24; PDD-NOS n=18) based on DSM-IV criteria, the Autism Diagnostic Interview (ADI) and Autism Diagnostic Observation Schedule. The sample was divided into two groups: on-time versus delayed-onset of phrase speech. Milestone data was collected retrospectively through the ADI interview. The Vineland Adaptive Behavior Scale (VABS) was used to measure functional communication and socialization. Because of its previously demonstrated predictive power, a sentence repetition task was used to estimate current core language abilities.
The on-time language milestone group achieved higher scores on three measures of cognitive ability including verbal ability, nonverbal ability, and full scale IQ (all ps<.05). After controlling for nonverbal ability, the delayed language milestone group showed greater impairment in structural language and functional communication, but not functional social skills.
We find that milestones are useful for capturing language performance at school age even in high functioning, verbal children on the autism spectrum. When a detailed assessment of language is not possible, data on early milestones may be useful for treatment planning in clinical settings and language phenotyping in the laboratory. Language milestones might offer an easy, early-available method for parsing the heterogeneity in ASD that confounds many inquiries into its biology. Milestone information can also be used by pediatricians and other practitioners when they are predicting trajectories and as an impetus for early intensive language intervention even for children with HF-ASD.