Predicting the path of language development in ASD

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This study looked at… well, it looked at a whole bunch of things, so let’s take a step back. You’ve all heard of ASD infant sibling studies, right? Those are where the researchers take a group of high risk infants (because they have siblings with ASD) and compare development to low risk infants (who have siblings who do not have ASD). These studies are popular in longitudinal studies of autism because the researchers have a better chance of observing the developmental trajectories of children with ASD before, during, and after diagnosis.

Now that we’re up to speed on the rationale, let’s get into the specifics. Franchini, et al. assessed 660 infants over a 2.5 year span to measure the trajectory of language development, as well as predictors for development and outcome of language and autism diagnoses.

The authors identified trends in groups of children from 6 to 36 months for a bunch of tests, including the:

If you regularly use any of these tests in your practice, this article may be good to have because it gives a ton of data on what to expect over time in these tests for children with and without autism, and those who are and aren’t high risk.

But what we really want to know as clinicians is—what differentiated those who went on to have an autism diagnosis from those who didn’t?

A big predictor was gesture. Using the MacArthur Communicative Development Inventory, Words and Gestures form (M-CDI), gestures (including aspects of joint attention and pretend play) at 12 months predicted risk category and ASD diagnosis. The authors state, “…a lower rate of gesture use by the first birthday can be associated with a later ASD diagnosis.”

Children who were diagnosed with ASD also tended to follow slower-developing trajectories of both language reception and expression. About 33% later demonstrated language delay (measured by 1.5 standard deviations below the mean on the language portions of the MSEL).

Interestingly, motor skills are playing some sort of role here as well. Gross and fine motor skills were positively associated with gesture development. The authors posit that good motor skills support gesture, which bolsters early language. Though they don’t yet have data to fully support this, they wonder if motor skills may need to be targeted in early intervention programs for the benefit to language, in addition to the benefit they have on movement development, and suggest this as an area for future exploration.

 

Franchini, M., Duku, E., Armstrong, V., Brian, J., Bryson, S. E., Garon, N., … & Smith, I. M. (2018). Variability in verbal and nonverbal communication in infants at risk for autism spectrum disorder: Predictors and outcomes. Journal of Autism and Developmental Disorders. Advance online publication. doi: 10.1007/s10803-018-3607-9.